Managed resources are becoming more and more popular in drivers. Let's
implement managed polled input devices, to complement managed regular input
devices.

Similarly to managed regular input devices only one new call
devm_input_allocate_polled_device() is added and the rest of APIs is
modified to work with both managed and non-managed devices.
Reviewed-by: NDavid Herrmann <dh.herrmann@gmail.com>
Tested-by: NAlexander Shiyan <shc_work@mail.ru>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Sysfs entry for reading and setting of the polling interval. If the
interval is set to 0, polling is stopped. Polling is restarted when
interval is changed to non-zero.

sysfs entries:
poll = current polling interval in msec (RW)
max = max allowed polling interval (RO)
min = min allowed polling interval (RO)

Minimum and maximum limit for interval can be set while setting up the
device.

Interval can be adjusted even if the input device is not currently open.

[dtor@mail.ru: add kernel doc markup for the new fields]
Signed-off-by: NSamu Onkalo <samu.p.onkalo@nokia.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Optional open and close methods for preparing and closing
the device.
Signed-off-by: NSamu Onkalo <samu.p.onkalo@nokia.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

input-polldev provides a skeleton for supporting simple input
devices that need to be periodically scanned or polled to
detect changes in their state.
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>