ALSA: hda - Add fixup for ASUS N56VZ

ASUS N56VZ needs a fixup for the bass speaker pin, which was already
provided via model=asus-mode4.

Bugzilla: https://bugzilla.novell.com/show_bug.cgi?id=841645
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>