ASoC: Fix snd_soc_{new,free}_ac97_codec() locking removal

Commit e3f205a72c45 ("ASoC: Remove locking in
snd_soc_{new,free}_ac97_codec()") overlooked a unlock on one of the error
paths.

Fixes: e3f205a72c45 ("ASoC: Remove locking in snd_soc_{new,free}_ac97_codec()")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-core.c

@@ -2115,7 +2115,6 @@ int snd_soc_new_ac97_codec(struct snd_soc_codec *codec,
 	if (codec->ac97->bus == NULL) {
 		kfree(codec->ac97);
 		codec->ac97 = NULL;
-		mutex_unlock(&codec->mutex);
 		return -ENOMEM;
 	}