[ALSA] hda-codec - Fix 5.1 output in LG LW20

Implemented LG LW20 5.1 support based on ALC880 threestack modes. It was
previously set to use one DAC and 2 jack modes, giving 2-channel output
only. Analog CD playing support is still missing.

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