ALSA: usb-audio: Exclude Scarlett 18i20 1st Gen from SKIP_IFACE_SETUP

Same issue as the other 1st Gen Scarletts: QUIRK_FLAG_SKIP_IFACE_SETUP
causes distorted audio on the Scarlett 18i20 1st Gen (1235:800c).

Fixes: 38c3220 ("ALSA: usb-audio: Add QUIRK_FLAG_SKIP_IFACE_SETUP")
Reported-by: tucktuckg00se [geoffreybennett/linux-fcp#54]
Signed-off-by: Geoffrey D. Bennett <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>

Author: geoffreybennett

sound/usb/quirks.c

@@ -2501,6 +2501,7 @@ static const struct usb_audio_quirk_flags_table quirk_flags_table[] = {
 		   QUIRK_FLAG_VALIDATE_RATES),
 	DEVICE_FLG(0x1235, 0x8006, 0), /* Focusrite Scarlett 2i2 1st Gen */
 	DEVICE_FLG(0x1235, 0x800a, 0), /* Focusrite Scarlett 2i4 1st Gen */
+	DEVICE_FLG(0x1235, 0x800c, 0), /* Focusrite Scarlett 18i20 1st Gen */
 	DEVICE_FLG(0x1235, 0x8016, 0), /* Focusrite Scarlett 2i2 1st Gen */
 	DEVICE_FLG(0x1235, 0x801c, 0), /* Focusrite Scarlett Solo 1st Gen */
 	VENDOR_FLG(0x1235, /* Focusrite Novation */