Add a simple driver for pwm driver LEDs.  pwm_id and period can be defined
in board file.  It is developed for pxa, however it is probably generic
enough to be used on other platforms with pwm.
Signed-off-by: NLuotao Fu <l.fu@pengutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NRichard Purdie <rpurdie@linux.intel.com>