ALSA: pcm: Add snd_pcm_stop_xrun() helper

Add a new helper function snd_pcm_stop_xrun() to the standard sequnce
lock/snd_pcm_stop(XRUN)/unlock by a single call, and replace the
existing open codes with this helper.

The function checks the PCM running state to prevent setting the wrong
state, too, for more safety.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/firewire/isight.c b/sound/firewire/isight.c
index 7ac9443..48d6dca 100644
--- a/sound/firewire/isight.c
+++ b/sound/firewire/isight.c
@@ -131,14 +131,8 @@
 
 static void isight_pcm_abort(struct isight *isight)
 {
-	unsigned long flags;
-
-	if (ACCESS_ONCE(isight->pcm_active)) {
-		snd_pcm_stream_lock_irqsave(isight->pcm, flags);
-		if (snd_pcm_running(isight->pcm))
-			snd_pcm_stop(isight->pcm, SNDRV_PCM_STATE_XRUN);
-		snd_pcm_stream_unlock_irqrestore(isight->pcm, flags);
-	}
+	if (ACCESS_ONCE(isight->pcm_active))
+		snd_pcm_stop_xrun(isight->pcm);
 }
 
 static void isight_dropped_samples(struct isight *isight, unsigned int total)