PIE tweak-a-roonie: Remove from lockscreen

there's no navigation bar regularly.. so why allow this. will save
on resources and eliminate the deadspot covering searchlight caused
by PIE's trigger zone.

Change-Id: I5c8a3cda1be755c95f96186801303d82297c827c

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