ASoC: Only deregister AC97 dev if it's name was not "AC97"

The commit 14fa43f5 ("ASoC: Only
register AC97 bus if it's not done already") added a condition for
calling of soc_ac97_dev_register() but not added for calling of
soc_ac97_dev_unregister().  This patch adds same condition for
soc_ac97_dev_unregister().  Without this fix, kernel crashes when
unloading an asoc driver.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/soc-core.c

@@ -1432,7 +1432,8 @@ void snd_soc_free_pcms(struct snd_soc_device *socdev)
 #ifdef CONFIG_SND_SOC_AC97_BUS
 	for (i = 0; i < codec->num_dai; i++) {
 		codec_dai = &codec->dai[i];
-		if (codec_dai->ac97_control && codec->ac97) {
+		if (codec_dai->ac97_control && codec->ac97 &&
+		    strcmp(codec->name, "AC97") != 0) {
 			soc_ac97_dev_unregister(codec);
 			goto free_card;
 		}