Decreases likelihood of AoD flickering

The transition from display power modes isn't tightly coupled
to the AoD lifecycle. We rely on a timeout to show and hide
the sysui scrim. In this case we increased it.

Change-Id: I13a0d33205c9f904afced63f231176151aee15c4
Fixes: 64077859
Test: receive notificaition in AoD, observe.