Input: mcs_touchkey - add support for suspend/resume

This adds support for system-level suspend/resume to the driver.

Signed-off-by: Heungjun Kim <riverful.kim@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>