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/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index 5cd5c96..805ce91 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -1524,8 +1524,9 @@
   Module snd-oxygen
   -----------------
 
-    Module for sound cards based on the C-Media CMI8787/8788 chip:
+    Module for sound cards based on the C-Media CMI8786/8787/8788 chip:
     * Asound A-8788
+    * Asus Xonar DG
     * AuzenTech X-Meridian
     * AuzenTech X-Meridian 2G
     * Bgears b-Enspirer