Currently headphone auto-mute using alc_automute_pin() assumes only
the single pin used for the headphone output.  Since there are devices
with multiple headphone jacks, we need to check all these pins there,
too.

Also this patch merges the common code between alc_automute_pin() and
alc_automute_amp() helper functions.
Signed-off-by: Takashi Iwai <tiwai@suse.de>