Revert "Add back navigation ring customization."

This reverts commit 38b969ba5a73f40ae56cdb48cf8f00ddf854f645.

Conflicts:
	core/java/android/provider/Settings.java
	core/res/res/values/symbols.xml
	packages/SystemUI/src/com/android/systemui/SearchPanelView.java

Change-Id: I891342d33f7b784ee9840900e05dd0a2d440513a