Update time when turning on screen, in addition to waking up

When in ambient display mode, we didn't get a callback to
onStartedWakingUp, thus the time was never refreshed. Since
broadcasts are disabled in this low-power state, we need to refresh
the clock manually before turning on the screen, because we can't
rely on the broadcasts to be delivered.

Bug: 23171638
Change-Id: I249f4195a14995f7c1467e73ac2aa400b871f80e