exynos4x12: liblights: generic button backlight implementation

http://review.cyanogenmod.org/#/c/48922/

Change-Id: I929fcb4f1c2a912e026328cb09f9be527adbaea9
vibrator intensity: disable tunable framework if not supported

Change-Id: I6481b82b7ee5412234d42e39f7f5560489f14af3
Merge changes I6481b82b,I929fcb4f into jb4.3

* changes:
  vibrator intensity: disable tunable framework if not supported
  exynos4x12: liblights: generic button backlight implementation