Notify Wake Lock Queue's EventFlag after write

Signal to the Wake Lock Queue's EventFlag that data has been written
to the queue. This allows for a reader of the queue to block until
data is available.

Bug: 122528664
Test: Verified Sensors HAL 2.0 default implementation properly reads
      the Wake Lock FMQ

Change-Id: I60f76e91c5b91d97156ad0328c10beb1111ba7b5
diff --git a/services/sensorservice/SensorDevice.h b/services/sensorservice/SensorDevice.h
index e1024ac..2a69654 100644
--- a/services/sensorservice/SensorDevice.h
+++ b/services/sensorservice/SensorDevice.h
@@ -238,6 +238,7 @@
     std::unique_ptr<WakeLockQueue> mWakeLockQueue;
 
     hardware::EventFlag* mEventQueueFlag;
+    hardware::EventFlag* mWakeLockQueueFlag;
 
     std::array<Event, SensorEventQueue::MAX_RECEIVE_BUFFER_EVENT_COUNT> mEventBuffer;