LED current is configurable via the sysfs.
 Max current is a read-only attribute.
 These attributes code can be shared in lp55xx common driver.

 Device attributes: 'led_current' and 'max_current'
 move to lp55xx common driver

 Replaced functions:
 show_max_current()  => lp55xx_show_max_current()
 show_current()      => lp55xx_show_current()
 store_current()     => lp55xx_store_current()

 LED setting function: set_led_current()
 Current registers are device specific, so configurable function is added
 in each driver.
Signed-off-by: NMilo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: NBryan Wu <cooloney@gmail.com>

 lp5521_set_brightness() and lp5523_set_brightness() are replaced with
 common function, lp55xx_set_brightness().
 This function is invoked when the brightness of each LED channel is updated.
 LP5521 and LP5523 have different register address for the brightness control,
 so this work is done by chip specific brightness_work_fn().

 lp5521/5523_led_brightness_work():
 use lp55xx_led and lp55xx_chip data structure.
 use lp55xx write function.
Signed-off-by: NMilo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: NBryan Wu <cooloney@gmail.com>

 lp5521_init_led() and lp5523_init_led() are replaced with one common function,
 lp55xx_init_led().
 Max channels is configurable, so it's used in lp55xx_init_led().

 'LP5523_LEDS' are changed to 'LP5523_MAX_LEDS'.

 lp55xx_set_brightness, lp55xx_led_attributes: skeleton
 Will be filled in next patches.
Signed-off-by: NMilo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: NBryan Wu <cooloney@gmail.com>

 LED class devices are registered in lp5521_register_leds() and
 lp5523_register_leds().
 Two separate functions are merged into consolidated lp55xx function,
 lp55xx_register_leds().

 Error handling fix:
 Unregistering LEDS are handled in lp55xx_register_leds() when LED registration
 failure occurs. So each driver error handler is changed to 'err_register_leds'

 Chip dependency: 'brightness_work_fn' and 'set_led_current'
 To make the structure abstract, both functions are configured in each driver.
 Those functions should be done by each driver because register control is
 chip-dependant work.

 lp55xx_init_led: skeleton
 Will be filled in next patch
Signed-off-by: NMilo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: NBryan Wu <cooloney@gmail.com>

 Two separate de-init functions are merged into one common function.
 And it is used in err_post_init of lp55xx_init_device().
Signed-off-by: NMilo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: NBryan Wu <cooloney@gmail.com>

 lp5521/5523_init_device() are replaced with lp55xx common function,
 lp55xx_init_device().

 Error handler in init_device:
 deinit function are matched with 'err_post_init' section in
 lp55xx_init_device().

 Remove LP5523 engine intialization code:
 Engine functionality is not mandatory but optional.
 Moreover engine initialization is done internally with device reset command.
 Therefore, this code is unnecessary.
Signed-off-by: NMilo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: NBryan Wu <cooloney@gmail.com>

 LP5521/5523 chip configuration is replaced with lp55xx common function,
 lp55xx_post_init_device().

 Name change:
 lp5521/5523_configure() to lp5521/5523_post_init_device()
 These are called in init function.

 Register access function
 Argument type is changed from 'i2c_client' to 'lp55xx_chip'.
 Use exported R/W functions of lp55xx common driver.

 Temporary variables in lp5521/5523_init_device()
 These functions will be removed but temporary variables are needed for
 blocking build warnings - incompatible pointer.
Signed-off-by: NMilo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: NBryan Wu <cooloney@gmail.com>

 LP5521/5523 chip detection functions are replaced with lp55xx common function,
 lp55xx_detect_device().
 Chip dependent address and values are configurable in each driver.
 In init function, chip detection is executed.
Signed-off-by: NMilo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: NBryan Wu <cooloney@gmail.com>

 LP5521/5523 reset device functions are moved to lp55xx common driver.
 Value of register address and value are chip dependent.
 Those are configured in each driver.
 In init function, reset command is executed.
Signed-off-by: NMilo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: NBryan Wu <cooloney@gmail.com>

 LP5521/5523 platform data functions are moved to lp55xx common driver.
 New init function, lp55xx_init_device() is created.
Signed-off-by: NMilo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: NBryan Wu <cooloney@gmail.com>

 This patch supports basic common driver code for LP5521, LP5523/55231 devices.

 ( Driver Structure Data )

 lp55xx_led and lp55xx_chip
 In lp55xx common driver, two different data structure is used.
 o lp55xx_led
   control multi output LED channels such as led current, channel index.
 o lp55xx_chip
   general chip control such like the I2C and platform data.

 For example, LP5521 has maximum 3 LED channels.
 LP5523/55231 has 9 output channels.

 lp55xx_chip for LP5521 ... lp55xx_led #1
                            lp55xx_led #2
                            lp55xx_led #3

 lp55xx_chip for LP5523 ... lp55xx_led #1
                            lp55xx_led #2
                            .
                            .
                            lp55xx_led #9

 ( Platform Data )

 LP5521 and LP5523/55231 have own specific platform data.
 However, this data can be handled with just one platform data structure.
 The lp55xx platform data is declared in the header.
 This structure is derived from leds-lp5521.h and leds-lp5523.h
Signed-off-by: NMilo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: NBryan Wu <cooloney@gmail.com>