ALSA: hda/realtek - Update headset mode for ALC256

ALC255 and ALC256 were some difference for hidden register.
This update was suitable for ALC256.

Fixes: e69e7e03

 ("ALSA: hda/realtek - ALC256 speaker noise issue")
Signed-off-by: Kailang Yang <kailang@realtek.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>