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/sound/pci/Kconfig b/sound/pci/Kconfig
index 82b9bdd..21d117a 100644
--- a/sound/pci/Kconfig
+++ b/sound/pci/Kconfig
@@ -744,7 +744,8 @@
 	select SND_OXYGEN_LIB
 	help
 	  Say Y here to include support for sound cards based on the
-	  Asus AV100/AV200 chips, i.e., Xonar D1, DX, D2 and D2X.
+	  Asus AV100/AV200 chips, i.e., Xonar D1, DX, D2, D2X, and
+	  Essence STX.
 	  Support for the HDAV1.3 (Deluxe) is very experimental.
 
 	  To compile this driver as a module, choose M here: the module