[ALSA] hda-codec - Enable VIA SPDIF input pin

Enable the SPDIF input-pin on VIA codecs when SPDIF-input is enabled
by BIOS.  Also, including a bit code clean up.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>