[ALSA] Add support of LG LW20 laptop

Add support of LG LW20 laptop with ALC880 codec (ALSA bug#1572).

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 1def604..baf18c6 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -701,6 +701,7 @@
 	  uniwill	3-jack
 	  F1734		2-jack
 	  lg		LG laptop (m1 express dual)
+	  lg-lw		LG LW20 laptop
 	  test		for testing/debugging purpose, almost all controls can be
 			adjusted.  Appearing only when compiled with
 			$CONFIG_SND_DEBUG=y