ALSA: usb-audio: Add DSD support for Gustard U16/X26 USB Interface

This patch adds native DSD support for Gustard U16/X26 USB Interface.
Tested using VID and fp->dsd_raw method.
Signed-off-by: Justin Song <flyingecar@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/CA+9XP1ipsFn+r3bCBKRinQv-JrJ+EHOGBdZWZoMwxFv0R8Y1MQ@mail.gmail.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/quirks.c

@@ -1657,6 +1657,7 @@ u64 snd_usb_interface_dsd_format_quirks(struct snd_usb_audio *chip,
 	case 0x23ba:  /* Playback Designs */
 	case 0x25ce:  /* Mytek devices */
 	case 0x278b:  /* Rotel? */
+	case 0x292b:  /* Gustard/Ess based devices */
 	case 0x2ab6:  /* T+A devices */
 	case 0x3842:  /* EVGA */
 	case 0xc502:  /* HiBy devices */