OMAP4 keyboard controller includes:
  - built-in scanning algorithm
  - debouncing feature

Driver implementation is based on matrix_keypad.c
Signed-off-by: NSyed Rafiuddin <rafiuddin.syed@ti.com>
Signed-off-by: NAbraham Arce <x0066660@ti.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>