[ALSA] hda-codec - Support of Lenovo Thinkpad X300

Added the model thinkpad for Lenovo Thinkpad X300 with AD1984A codec.

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 b0240439..42dd8f5 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -923,6 +923,7 @@
 	  desktop	3-stack desktop (default)
 	  laptop	laptop with HP jack sensing
 	  mobile	mobile devices with HP jack sensing
+	  thinkpad	Lenovo Thinkpad X300
 
 	AD1884
 	  N/A