ALSA: sound/usb/format: silence uninitialized variable warnings

Gcc complains that ret might be used uninitialized:

sound/usb/format.c: In function ‘snd_usb_parse_audio_format’:
sound/usb/format.c:354: warning: ‘ret’ may be used uninitialized in this function
sound/usb/format.c:354: note: ‘ret’ was declared here
sound/usb/format.c:414: warning: ‘ret’ may be used uninitialized in this function
sound/usb/format.c:414: note: ‘ret’ was declared here

I suppose it could be uninitialized if there is ever a UAC_VERSION_3
released. Anyway this patch is worthwhile if only to silence the gcc
warning.

Signed-off-by: Dan Carpenter <[e-mail]>
Acked-by: Daniel Mack <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>

sound/usb/format.c

···
 		/* fp->channels is already set in this case */
 		ret = parse_audio_format_rates_v2(chip, fp);
 		break;
+	default:
+		snd_printk(KERN_ERR "%d:%u:%d : invalid protocol version %d\n",
+			   chip->dev->devnum, fp->iface, fp->altsetting, protocol);
+		return -EINVAL;
 	}
 
 	if (fp->channels < 1) {
···
 		ret = parse_audio_format_rates_v2(chip, fp);
 		break;
 	}
+	default:
+		snd_printk(KERN_ERR "%d:%u:%d : invalid protocol version %d\n",
+			   chip->dev->devnum, fp->iface, fp->altsetting, protocol);
+		return -EINVAL;
 	}
 
 	return ret;