[ALSA] Add Native Instrument usb audio device support

Add snd-usb-caiaq driver to support caiaq usb-audio devices from
Native Instrument:
	* Native Instruments RigKontrol2
	* Native Instruments Kore Controller
	* Native Instruments Audio Kontrol 1
	* Native Instruments Audio 8 DJ

Signed-off-by: Daniel Mack <daniel@caiaq.org>
Signed-off-by: Karsten Wiese <fzu@wemgehoertderstaat.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>