ALSA: usb-audio: Add native DSD support for PS Audio NuWave DAC

This patch adds native DSD support for the PS Audio NuWave DAC.

Signed-off-by: Jurgen Kramer <gtmkramer@xs4all.nl>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>