AOD: Avoid double re-registration of sensors

Bug: 62940557
Test: adb shell setprop log.tag.DozeService DEBUG; adb kill `pid systemui`; adb logcat -s DozeSensors, verify sensors are only reregistered, not registered, unregistered and reregistered after unpausing AOD
Change-Id: I362eca377ec67e986c7aef8ad81ce261a6f3fd68
1 file changed