ALSA: snd-usb: properly initialize the sync endpoint

Jeffrey Barish reported an obvious bug in the pcm part of the usb-audio
driver which causes the code to not initialize the sync endpoint from
configure_endpoint().
Reported-by: NJeffrey Barish <jeff_barish@earthlink.net>
Signed-off-by: NDaniel Mack <zonque@gmail.com>
Cc: stable@kernel.org [3.5+]
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/usb/pcm.c

@@ -459,7 +459,7 @@ static int configure_endpoint(struct snd_usb_substream *subs)
 		return ret;
 
 	if (subs->sync_endpoint)
-		ret = snd_usb_endpoint_set_params(subs->data_endpoint,
+		ret = snd_usb_endpoint_set_params(subs->sync_endpoint,
 						  subs->pcm_format,
 						  subs->channels,
 						  subs->period_bytes,