ALSA: usb-audio: Add DSD support for Comtrue USB Audio device

[ Upstream commit e9df175 ]

The vendor Comtrue Inc. (0x2fc6) produces USB audio chipsets like
the CT7601 which are capable of Native DSD playback.

This patch adds QUIRK_FLAG_DSD_RAW for Comtrue (VID 0x2fc6), which enables
native DSD playback (DSD_U32_LE) on their USB Audio device. This has been
verified under Ubuntu 25.04 with JRiver.

Signed-off-by: noble.yang <noble.yang@comtrue-inc.com>
Link: https://patch.msgid.link/20250731110614.4070-1-noble228@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: noble.yang

sound/usb/quirks.c

@@ -2405,6 +2405,8 @@ static const struct usb_audio_quirk_flags_table quirk_flags_table[] = {
 		   QUIRK_FLAG_DSD_RAW),
 	VENDOR_FLG(0x2d87, /* Cayin device */
 		   QUIRK_FLAG_DSD_RAW),
+	VENDOR_FLG(0x2fc6, /* Comture-inc devices */
+		   QUIRK_FLAG_DSD_RAW),
 	VENDOR_FLG(0x3336, /* HEM devices */
 		   QUIRK_FLAG_DSD_RAW),
 	VENDOR_FLG(0x3353, /* Khadas devices */