AOD: Skip prox check if cached prox value available

On AOD, we run the proximity sensor, so when a pulse comes in,
there is no need to wait for a new result. Instead, we can use
the existing value if available.

Change-Id: Ibded081e5011a3053e6990012f97f63865e20298
Fixes: 63538693
Test: receive notification, verify that pulsing starts immediately and does not wait for the proximity check.