Setup overlay for single-color notification LED.

Remove option to change color of notification LED as it is single-color.

This relies on Michaels' following commits.  Do not merge first!!!

Add support for single color notification LED (1/2)
http://review.cyanogenmod.org/#/c/70688/

Add support for single color notification LED (2/2)
http://review.cyanogenmod.org/#/c/70702/

Change-Id: I1df6bad3608b0fa9daf3030704b3f1f78c7c0336