ALSA: usb-audio: add implicit fb quirk for Axe-Fx II

The Axe-Fx II implicit feedback end point and the data sync endpoint
are in different interface descriptors. Add quirk to ensure a sync
endpoint is properly configured.

Signed-off-by: Alberto Aguirre <albaguirre@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/pcm.c

@@ -348,6 +348,16 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 
 		alts = &iface->altsetting[1];
 		goto add_sync_ep;
+	case USB_ID(0x2466, 0x8003):
+		ep = 0x86;
+		iface = usb_ifnum_to_if(dev, 2);
+
+		if (!iface || iface->num_altsetting == 0)
+			return -EINVAL;
+
+		alts = &iface->altsetting[1];
+		goto add_sync_ep;
+
 	}
 	if (attr == USB_ENDPOINT_SYNC_ASYNC &&
 	    altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&