AOD: avoid flicker when turning off screen

Avoids a flicker during the turn off sequence where
the status bar would not enter the keyguard mode until
after AOD has already shown.

To avoid this, now also show keyguard if dozing and
the device is not yet fully asleep as long as the
screen is off.

Change-Id: Ic90b33a368332c9a7d7202b4e25a6c7c23b6506c
Fixes: 36506840
Test: Enable AOD, go to home screen, press power. Verify that there is no flicker in the transition to AOD.