Notify HAL when events are read

As defined in the HAL specification, the client of the HAL (framework or
VTS) needs to set the EVENTS_READ flag when it fetches samples out of
the FMQ, to support blocking write mode.

Bug: 135442877
Test: run VTS on a device supporting HAL 2.0
Change-Id: Ic7755e869b999b638086275e4e579a84600be314

sensors/2.0/vts/functional/SensorsHidlEnvironmentV2_0.cpp

@@ -139,6 +139,7 @@ void SensorsHidlEnvironmentV2_0::readEvents() {
     size_t eventsToRead = std::min(availableEvents, mEventBuffer.size());
     if (eventsToRead > 0) {
         if (mEventQueue->read(mEventBuffer.data(), eventsToRead)) {
+            mEventQueueFlag->wake(asBaseType(EventQueueFlagBits::EVENTS_READ));
             for (size_t i = 0; i < eventsToRead; i++) {
                 addEvent(mEventBuffer[i]);
             }