Alsa: fix QAudioOutput state after resume().

In push mode, the state must be IdleState after resume(), and only
change to ActiveState once it receives some data.

Task-number: QTBUG-50390
Change-Id: Idd08d8826f00d943b3bf750524f811874e010149
Reviewed-by: Pasi Petäjäjärvi <pasi.petajajarvi@theqtcompany.com>

src/plugins/alsa/qalsaaudiooutput.cpp

@@ -651,7 +651,7 @@ void QAlsaAudioOutput::resume()
         }
         resuming = true;
 
-        deviceState = QAudio::ActiveState;
+        deviceState = pullMode ? QAudio::ActiveState : QAudio::IdleState;
 
         errorState = QAudio::NoError;
         timer->start(period_time/1000);