ALSA: oxygen: Xonar DG(X): move the mixer code into another file

Moving the mixer code away makes things easier. The mixer
will control the driver, so the functions of the
driver need to be non-static.

Signed-off-by: Roman Volkov <v1ron@mail.ru>
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
diff --git a/sound/pci/oxygen/Makefile b/sound/pci/oxygen/Makefile
index 0f87265..8f4c409 100644
--- a/sound/pci/oxygen/Makefile
+++ b/sound/pci/oxygen/Makefile
@@ -1,5 +1,5 @@
 snd-oxygen-lib-objs := oxygen_io.o oxygen_lib.o oxygen_mixer.o oxygen_pcm.o
-snd-oxygen-objs := oxygen.o xonar_dg.o
+snd-oxygen-objs := oxygen.o xonar_dg_mixer.o xonar_dg.o
 snd-virtuoso-objs := virtuoso.o xonar_lib.o \
 	xonar_pcm179x.o xonar_cs43xx.o xonar_wm87x6.o xonar_hdmi.o