display: Make advanced settings a category

This was a separate screen but it's too empty for that, let's make
it a category like in CM11 for now. If it ever becomes a separate
screen it needs its own fragment so that navigation is possible
via actionbar.

Change-Id: I4b1f3e78a013412d5e39847683ca622dc76b9fa1

Conflicts:
	res/xml/display_settings.xml
	src/com/android/settings/DisplaySettings.java

 Author:    Diogo Ferreira <defer@cyngn.com>
Port: Wake on plug (2/2)

Change-Id: Icdacf8b186d893c2a107d9d61aa5439d777f4523