ALSA: sparc: fix missing unlock on error in snd_cs4231_playback_prepare()

Add the missing unlock before return from function
snd_cs4231_playback_prepare() in the error handling
case.

Fixes: 5a19b178d7b4 ('ALSA: sparc/cs4231: Use WARN_ON() instead of BUG_ON()')
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/sparc/cs4231.c

@@ -907,19 +907,24 @@ static int snd_cs4231_playback_prepare(struct snd_pcm_substream *substream)
 	struct snd_cs4231 *chip = snd_pcm_substream_chip(substream);
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	unsigned long flags;
+	int ret = 0;
 
 	spin_lock_irqsave(&chip->lock, flags);
 
 	chip->image[CS4231_IFACE_CTRL] &= ~(CS4231_PLAYBACK_ENABLE |
 					    CS4231_PLAYBACK_PIO);
 
-	if (WARN_ON(runtime->period_size > 0xffff + 1))
-		return -EINVAL;
+	if (WARN_ON(runtime->period_size > 0xffff + 1)) {
+		ret = -EINVAL;
+		goto out;
+	}
 
 	chip->p_periods_sent = 0;
+
+out:
 	spin_unlock_irqrestore(&chip->lock, flags);
 
-	return 0;
+	return ret;
 }
 
 static int snd_cs4231_capture_hw_params(struct snd_pcm_substream *substream,