[ALSA] hda: STAC927x VREF fix

Some laptops incorrectly assume the front input jack as a line in
instead of a microphone in. Which in turn disables the voltage
reference, in which non-amplified input is not possible.  This patch
enables VREF80 for the input jack.

Signed-off-by: Matthew Ranostay <mranostay@embeddedalley.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>