Preventing keyguard dismissal when screen is off.

For automotive, we dismiss keyguard to go straight to the home screen
or the bouncer. However, when the screen is off, we want keyguard to remain
to properly stop the applications.

We dismiss keyguard when the screen comes back on.

Fixes: 133324766
Bug: 133271311
Test: manual, turning screen on and off repeatedly, switching users while
screen is off or on, reboots

Change-Id: Iced146ad8753794bb766eb528dd198f886ccf3d7