Add M2Tech hiFace USB-SPDIF driver

Add driver for M2Tech hiFace USB-SPDIF interface and compatible devices.

M2Tech hiFace and compatible devices offer a Hi-End S/PDIF Output
Interface, see http://www.m2tech.biz/hiface.html

The supported products are:

  * M2Tech Young
  * M2Tech hiFace
  * M2Tech North Star
  * M2Tech W4S Young
  * M2Tech Corrson
  * M2Tech AUDIA
  * M2Tech SL Audio
  * M2Tech Empirical
  * M2Tech Rockna
  * M2Tech Pathos
  * M2Tech Metronome
  * M2Tech CAD
  * M2Tech Audio Esclusive
  * M2Tech Rotel
  * M2Tech Eeaudio
  * The Chord Company CHORD
  * AVA Group A/S Vitus

Signed-off-by: Antonio Ospite <ao2@amarulasolutions.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/Kconfig b/sound/usb/Kconfig
index 225dfd7..de9408b 100644
--- a/sound/usb/Kconfig
+++ b/sound/usb/Kconfig
@@ -115,5 +115,36 @@
           and further help can be found at
           http://sixfireusb.sourceforge.net
 
+config SND_USB_HIFACE
+        tristate "M2Tech hiFace USB-SPDIF driver"
+        select SND_PCM
+        help
+	  Select this option to include support for M2Tech hiFace USB-SPDIF
+	  interface.
+
+	  This driver supports the original M2Tech hiFace and some other
+	  compatible devices. The supported products are:
+
+	    * M2Tech Young
+	    * M2Tech hiFace
+	    * M2Tech North Star
+	    * M2Tech W4S Young
+	    * M2Tech Corrson
+	    * M2Tech AUDIA
+	    * M2Tech SL Audio
+	    * M2Tech Empirical
+	    * M2Tech Rockna
+	    * M2Tech Pathos
+	    * M2Tech Metronome
+	    * M2Tech CAD
+	    * M2Tech Audio Esclusive
+	    * M2Tech Rotel
+	    * M2Tech Eeaudio
+	    * The Chord Company CHORD
+	    * AVA Group A/S Vitus
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called snd-usb-hiface.
+
 endif	# SND_USB