ALSA: hda: document VIA models

Add documentation about the autodetection of the VIA codec models to
avoid the false impression that they are not supported.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/Documentation/sound/alsa/HD-Audio-Models.txt b/Documentation/sound/alsa/HD-Audio-Models.txt
index 03771d7..84b2375 100644
--- a/Documentation/sound/alsa/HD-Audio-Models.txt
+++ b/Documentation/sound/alsa/HD-Audio-Models.txt
@@ -416,3 +416,7 @@
   mbp55		MacBook Pro 5,5
   imac27	IMac 27 Inch
   auto		BIOS setup (default)
+
+VIA VT17xx/VT18xx/VT20xx
+========================
+  auto		BIOS setup (default)