ALSA: usb-audio: Add implicit feedback quirk for UR22C

This uses the same quirk as the Motu and SSL2 devices.
Tested on the UR22C.

Fixes bug 208851.

Signed-off-by: Joshua Sivec <sivec@posteo.net>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=208851
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200825165515.8239-1-sivec@posteo.net
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/pcm.c

@@ -369,6 +369,7 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 	case USB_ID(0x07fd, 0x0008): /* MOTU M Series */
 	case USB_ID(0x31e9, 0x0001): /* Solid State Logic SSL2 */
 	case USB_ID(0x31e9, 0x0002): /* Solid State Logic SSL2+ */
+	case USB_ID(0x0499, 0x172f): /* Steinberg UR22C */
 	case USB_ID(0x0d9a, 0x00df): /* RTX6001 */
 		ep = 0x81;
 		ifnum = 2;