AudioTrack: Allow flush in flush state to clear subsequent written data

am: 4c5ed30aeb

Change-Id: Ie5e96925aa26850e9bd03f9224ae460301783538

media/libaudioclient/AudioTrack.cpp

@@ -806,7 +806,7 @@ void AudioTrack::flush()
         return;
     }
     AutoMutex lock(mLock);
-    if (mState == STATE_ACTIVE || mState == STATE_FLUSHED) {
+    if (mState == STATE_ACTIVE) {
         return;
     }
     flush_l();