ALSA: usb-audio: add quirk for Pioneer DDJ-RB

This is just another Pioneer device with fixed endpoints. Input is dummy
but used as feedback (it always returns silence).

Cc: stable@vger.kernel.org
Signed-off-by: Hector Martin <marcan@marcan.st>
Link: https://lore.kernel.org/r/20200810082502.225979-1-marcan@marcan.st
Signed-off-by: Takashi Iwai <tiwai@suse.de>