Avoid SysUI force close due a miss check of ENABLE_HEADS_UP
Thanks cristianomatos
Revert "fb: Show heads up at the bottom of the screen (1/2)"

This reverts commit 8a00ecb6a255f25544de6676149c3626642a95ae.

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/notification/HoverLayout.java
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java