Refresh screen off timeout when screen lock is released in VR

When evaluating conditions for user activity with no lights change,
treat POLICY_VR the same way as for POLICY_BRIGHT, so new activity
timeout will be set.

Bug: 37968591
Test: Set screen timeout to 15s, launch Daydream, wait, launch Welcome flow.
Change-Id: I3185cc97364ae5631ef53906958b16d41f326c3b