alsa: force playback start when buffer is full

When we try to play data but the ringbuffer is full, we need to start
the device or else we will stay in this situation forever and stay
silent.

Fixes #2830

spa/plugins/alsa/alsa-pcm.c

@@ -2128,7 +2128,7 @@ again:
 
 	state->sample_count += total_written;
 
-	if (SPA_UNLIKELY(!state->alsa_started && total_written > 0))
+	if (SPA_UNLIKELY(!state->alsa_started && (total_written > 0 || frames == 0)))
 		do_start(state);
 
 	return 0;