Hold Display Suspend blocker when going to Doze

The transition to Doze is asynchronous from the release of the display
suspend blocker.  This created a race condition where we could
potentially suspend before Doze service had a chance to transition to
Doze. This change holds the Display Suspend blocker until Doze service
acquires the DOZE lock.

Bug: 138828701
Test: atest PowerManagerService
Test: Manual, verify no repro of the bug.  Additional verify the device
does release the Display suspend blocker once we are in DOZE.

Change-Id: I777bc7963b1ab445378164b0f4d3f79113510b81