ALSA: hda - Add headphone automute support for 3stack-hp model (ALC888)

Mute speaker outputs on headphone insertion for machines that use
3stack-hp model.

Signed-off-by: Herton Ronaldo Krzesinski <herton@mandriva.com.br>
Signed-off-by: Takashi Iwai <tiwai@suse.de>