ALSA: usb-mixer: factor out quirks

Move all non-standard mixer controls and vendor-specific extensions to a
separate file. Some structs need to be exported now.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/Makefile b/sound/usb/Makefile
index 0758d8d..744024a 100644
--- a/sound/usb/Makefile
+++ b/sound/usb/Makefile
@@ -4,6 +4,7 @@
 
 snd-usb-audio-objs := 	card.o \
 			usbmixer.o \
+			mixer_quirks.o \
 			proc.o \
 			quirks.o \
 			format.o \