ALSA: hda - Refactor input-pin parser for VIA codecs

patch_via.c has redundant codes for parsing the input-pins.  Although
they are pretty similar, but all implemented in different functions
just because of hard-coded ids and slight incompatibilities.
This patch refactors the codes to use the common helper function,
resulting in the reduction of many lines.
Signed-off-by: Takashi Iwai <tiwai@suse.de>