ALSA: usb-audio: refactor code

Clean up the usb audio driver by factoring out a lot of functions to
separate files. Code for procfs, quirks, urbs, format parsers etc all
got a new home now.

Moved almost all special quirk handling to quirks.c and introduced new
generic functions to handle them, so the exceptions do not pollute the
whole driver.

Renamed usbaudio.c to card.c because this is what it actually does now.
Renamed usbmidi.c to midi.c for namespace clarity.
Removed more things from usbaudio.h.

The non-standard drivers were adopted accordingly.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/endpoint.h

@@ -0,0 +1,11 @@
+#ifndef __USBAUDIO_ENDPOINT_H
+#define __USBAUDIO_ENDPOINT_H
+
+int snd_usb_parse_audio_endpoints(struct snd_usb_audio *chip,
+				  int iface_no);
+
+int snd_usb_add_audio_endpoint(struct snd_usb_audio *chip,
+			       int stream,
+			       struct audioformat *fp);
+
+#endif /* __USBAUDIO_ENDPOINT_H */