ALSA: hda - Add missing ALC680_* definitions

Also update the documentation.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Documentation/sound/alsa/HD-Audio-Models.txt

@@ -114,6 +114,11 @@ ALC662/663/272
   samsung-nc10	Samsung NC10 mini notebook
   auto		auto-config reading BIOS (default)
 
+ALC680
+======
+  base		Base model (ASUS NX90)
+  auto		auto-config reading BIOS (default)
+
 ALC882/883/885/888/889
 ======================
   3stack-dig	3-jack with SPDIF I/O

sound/pci/hda/patch_realtek.c

@@ -256,6 +256,13 @@ enum {
 	ALC882_MODEL_LAST,
 };
 
+/* ALC680 models */
+enum {
+	ALC680_BASE,
+	ALC680_AUTO,
+	ALC680_MODEL_LAST,
+};
+
 /* for GPIO Poll */
 #define GPIO_MASK	0x03
 
@@ -18997,7 +19004,8 @@ static void alc680_auto_init(struct hda_codec *codec)
  * configuration and preset
  */
 static const char *alc680_models[ALC680_MODEL_LAST] = {
-	[ALC680_BASE]		= "alc680_base",
+	[ALC680_BASE]		= "base",
+	[ALC680_AUTO]		= "auto",
 };
 
 static struct snd_pci_quirk alc680_cfg_tbl[] = {