[ALSA] usb: usbmixer error path fix

Without the patch below namelist[0] will not be freed in case
of kmalloc error.
Signed-off-by: NMariusz Kozlowski <m.kozlowski@tuxland.pl>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@suse.cz>

sound/usb/usbmixer.c

@@ -1526,7 +1526,7 @@ static int parse_audio_selector_unit(struct mixer_build *state, int unitid, unsi
 		namelist[i] = kmalloc(MAX_ITEM_NAME_LEN, GFP_KERNEL);
 		if (! namelist[i]) {
 			snd_printk(KERN_ERR "cannot malloc\n");
-			while (--i > 0)
+			while (i--)
 				kfree(namelist[i]);
 			kfree(namelist);
 			kfree(cval);