Cleanup.

Now that button and keyboard backlight don't use the HW framework
anymore, there's no point in having an abstraction for a single use case.

Change-Id: Ib66b2a29a105d53e3ba4273abb06977b132c1fc8
Settings: Modify AOSP EL translations

Change-Id: I7e3a59412a2884c26a5eb165676e381d003f0fca