ALSA: hda - Add a fix-up for Acer dmic with ALC271x codec

Acer laptops with ALC271x needs a magic initialization for digital-mic
to make it working with mono streams (and PulseAudio).
Added a fix-up applied to Acer with ALC271x generically.

Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>