drivers: input: Add touch disabler driver

 * Add driver for enabling and disabling the touch screen
   (and touch keys if available) when the screen powers on or off.

   This makes the use of a separate userspace program (a la InputDisabler)
   unnecessary.

 Squashed changes:

  f081fd8384fa input: touchscreen: Add touch disabler code to touch drivers

  * Add the function calls to touch_disabler_set_ts_dev() necessary
    for informing the touch disabler driver which input device should
    be switched on/off when the screen powers on or off.

  4faa86fcee57 input: keyboard: Add touch disabler code to touch drivers

  * Add the function calls to touch_disabler_set_tk_dev() necessary
    for informing the touch disabler driver which input device should
    be switched on/off when the screen powers on or off.

Change-Id: Iaad665039b5da1c7628581ba3d8288bda7862c35