Prevent quickscrub/switch from occuring when keyguard is up

When activity over lockscreen is visible and keyguard is up, user will
not be able to start quickscrub.

Change-Id: I018e0b448cdcc3d71a1f782959d633b7bc5dd627
Fixes: 73709365
Test: manual - at lockscreen launch camera and try to quickscrub