sound: virtuoso: add Xonar Essence STX support

Add support for the Asus Xonar Essence STX 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 841a936..1356d2a 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -1824,7 +1824,7 @@
   -------------------
 
     Module for sound cards based on the Asus AV100/AV200 chips,
-    i.e., Xonar D1, DX, D2, D2X and HDAV1.3 (Deluxe).
+    i.e., Xonar D1, DX, D2, D2X, HDAV1.3 (Deluxe), and Essence STX.
 
     This module supports autoprobe and multiple cards.