ALSA: snd-usb-caiaq: Fix the return of XRUN

Commit 3702b082 added a lock, but did not account for the case of
SNDRV_PCM_POS_XRUN, which would get immediately overwritten.

This could be bundled into one if-else-if statement, but the goto
helps to clarify the 'exceptional' case.

Thanks to Andreas Pape for spotting this.
Signed-off-by: Mark Hills <mark@pogo.org.uk>
Acked-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/caiaq/audio.c

@@ -311,8 +311,10 @@ snd_usb_caiaq_pcm_pointer(struct snd_pcm_substream *sub)
 
 	spin_lock(&dev->spinlock);
 
-	if (dev->input_panic || dev->output_panic)
+	if (dev->input_panic || dev->output_panic) {
 		ptr = SNDRV_PCM_POS_XRUN;
+		goto unlock;
+	}
 
 	if (sub->stream == SNDRV_PCM_STREAM_PLAYBACK)
 		ptr = bytes_to_frames(sub->runtime,
@@ -321,6 +323,7 @@ snd_usb_caiaq_pcm_pointer(struct snd_pcm_substream *sub)
 		ptr = bytes_to_frames(sub->runtime,
 					dev->audio_in_buf_pos[index]);
 
+unlock:
 	spin_unlock(&dev->spinlock);
 	return ptr;
 }