ALSA: hda - Fix headset mic detection problem for two Dell machines

One of them has the codec of alc256 and the other one has the codec
of alc289.

Cc: <stable@vger.kernel.org>
Signed-off-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>