We have a machine Dell XPS 13 with the codec alc256, after resume back
from S3, the headphone has noise when play sound.

Through comparing with the coeff vaule before and after S3, we found
restoring a coeff register will help remove noise.

BugLink: https://bugs.launchpad.net/bugs/1519168
Cc: Kailang Yang <kailang@realtek.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NHui Wang <hui.wang@canonical.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>