ALSA: hda - Add auto-mute support to PB desktop

Using the new chained_before flag, we can correct the headphone jack
detection capability easily over the existing ALC880 6stack model
(which disables the jack detection intentionally for compatibility
reason).

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=901846



Signed-off-by: Takashi Iwai <tiwai@suse.de>