[ALSA] hda-codec - Add LG LW20 line-in capture source

Add line-in to the list of LG LW20 capture sources. Also fix the LG LW
pin assignment list comment.

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>