ALSA: usb-audio: add check for faulty clock in parse_audio_format_rates_v2()

	int i, nr_rates, data_size, ret = 0;

	int clock = snd_usb_clock_find_source(chip, chip->ctrl_intf, fp->clock);

	if (clock < 0) {

		snd_printk(KERN_ERR "%s(): unable to find clock source (clock %d)\n",

				__func__, clock);

		goto err;

	}

	/* get the number of sample rates first by only fetching 2 bytes */

	ret = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_RANGE,

			      USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,