Keep ToggleLockscreenTiles in sync between Quick Settings and Ribbon

Update the appearance of both tiles when one is toggled.
Only the KeyguardLock which disabled the lockscreen is able to
re-enable it, so have both tiles use a static KeyguardLock.

Change-Id: Idd8d41d3eda60f9a13bd4b6bc0fab12eb3d25f40