ALSA: usb-audio: Add implicit feedback quirk for Qu-16

This patch fixes audio distortion on playback for the Allen&Heath
Qu-16.
Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201104115717.GA19046@b4.vuSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/pcm.c

@@ -336,6 +336,7 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 	switch (subs->stream->chip->usb_id) {
 	case USB_ID(0x0763, 0x2030): /* M-Audio Fast Track C400 */
 	case USB_ID(0x0763, 0x2031): /* M-Audio Fast Track C600 */
+	case USB_ID(0x22f0, 0x0006): /* Allen&Heath Qu-16 */
 		ep = 0x81;
 		ifnum = 3;
 		goto add_sync_ep_from_ifnum;