ALSA: hda/realtek: apply ALC891 headset fixup to one Dell machine

Without this patch, the headset-mic and headphone-mic don't work.

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