ALSA: hda: Add dock support for ThinkPad T550

Much like all the other Lenovo laptops, add a quirk to make
sound work with docking.

Reported-and-tested-by:  <lacknerflo@gmail.com>
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>