voice_thread.c ensure cpu gets re-boosted after Q_VOICE_STOP event

reset quiet counter after Q_VOICE_STOP

when the voice system is doing un-queued voice clips you can get a
voice_stop event which cancels the cpu boost but the quiet count was not reset
next clip will play unboosted causing stuttering

Change-Id: Icaada443e2399bf146e30bebee599db5b379063a

apps/voice_thread.c

@@ -421,6 +421,7 @@ static enum voice_state voice_message(struct voice_thread_data *td)
         /* Fall-through */
     case Q_VOICE_STOP:
         LOGFQUEUE("voice < Q_VOICE_STOP");
+        quiet_counter = 0;
         cancel_cpu_boost();
         voice_stop_playback();
         break;