Fix unnecessary relaunches when unlocking with fingerprint sensor.

When the device is unlocked using the fingerprint sensor in an
orientation opposite to the lockscreen orientation, the app that
will be visible is first relaunched in the current lockscreen
orientation and then later relaunched in the correct orientation.
If the keygaurd is going away then:
- Don't let keyguard affect device orientation. We want to use the
orientation of the app that will be visible.
- Allow the rotation sensor to be enabled even though draw isn't
complete so window manager can get the updated or last rotation
reading.
- Don't clear the previous proposed sensor reading to allow
window manager to use the information to update the orientation as
needed vs. falling back to the previous orientation.

Change-Id: I8369723d6a77f2c602f1ef080371fa7cd9ee094e
Fixes: 38494778
Test: Launch an app that doesn't fix orientation like clock, hold
the device in landscape, press the power button, unlock the device
using the fingerprint sensor, and verify the the app isn't
relaunched.