Unfreeze display even if screen is off

Change Idce8fc0049758e50aaf9bc3f93aff45758ed30c1 made it possible
for an animation to start and never complete, thus keeping the
display frozen.
So... disregard screen state when calling unfreeze. If mScreenRotationAnimation
isn't null, let it go all the way.

Change-Id: Ibf4b31508855398e8d20626bf169656e2a3d2aa9