ALSA: oxygen: add Xonar DG support

Add experimental support for the Asus Xonar DG sound card.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/oxygen/xonar_dg.h b/sound/pci/oxygen/xonar_dg.h
new file mode 100644
index 0000000..5688d78
--- /dev/null
+++ b/sound/pci/oxygen/xonar_dg.h
@@ -0,0 +1,8 @@
+#ifndef XONAR_DG_H_INCLUDED
+#define XONAR_DG_H_INCLUDED
+
+#include "oxygen.h"
+
+extern struct oxygen_model model_xonar_dg;
+
+#endif