Make 'Power button instantly locks' toggle work (1/2 framework)

If your device is secure (uses password/PIN/pattern) then the AOSP timeout settings are used.
But the 'Power button instantly locks' toggle is ignored. 'lockImmediately' in KeyguardViewMediator
is always set to true. This fix together with a settings fix switches to the the AOSP handling of this
setting.

Change-Id: Ic7ce8003f1b16a4feaa60ec81082c7ddfce23105