exynos4210: liblights: big cleanup

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

Change-Id: I5fa9602649c5d0e902dfc9ba9e50e8197d0dfb76
exynos4x12: liblights: generic button backlight implementation

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

Change-Id: I929fcb4f1c2a912e026328cb09f9be527adbaea9
Merge changes I929fcb4f,I5fa96026 into cm-10.2

* changes:
  exynos4x12: liblights: generic button backlight implementation
  exynos4210: liblights: big cleanup