universal8890: add support for AOD DT2W

   * Samsung touchscreens support using double-tap to wake to trigger
     always on display. Implement support for the sysfs API used to
     en/disable this. Note that this requires a kernel change to send
     KEY_POWER on the dt2w event instead of KEY_BLACK_UI_GESTURE - e.g.
     https://review.lineageos.org/c/LineageOS/android_kernel_samsung_universal8890/+/301195

   * [fcuzzocrea]: to simplify the logic of the original commit, another
     kernel change is needed :
     https://review.lineageos.org/c/LineageOS/android_kernel_samsung_universal8890/+/301231
     in this way, the AOD rectangle will not be cleared everytime the
     screen will be switched on, so it is not needed to set the
     rectangle everytime.
     Clearing the rectangle is something which is useful only on Samsung
     based ROMs which supports indeed different kinds of gestures when
     coupled with Samsung's smart cover.
     The only thing we support on AOSP is DT2W so it is safe to set the
     AOD rectangle as the whole panel area once and keep it.

   * Remove some white spaces while we are at it

Change-Id: I80898c8810216a90cc11b4e8b0f12a1918cd17a3