ALSA: HDA: Add fixup pins for Ideapad Y550

By adding the subwoofer as a speaker pin, it is treated correctly when auto-muting.

BugLink: https://launchpad.net/bugs/611803


Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>