ALSA: sparc: Add missing kfree in error path

If 'of_ioremap' fails, then 'amd' should be freed, otherwise, there is a
memory leak.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/sparc/amd7930.c

@@ -956,6 +956,7 @@ static int snd_amd7930_create(struct snd_card *card,
 	if (!amd->regs) {
 		snd_printk(KERN_ERR
 			   "amd7930-%d: Unable to map chip registers.\n", dev);
+		kfree(amd);
 		return -EIO;
 	}