ALSA: hda/realtek - Update ALC255 depop optimize

commit ab3b8e51 upstream.

Add ALC255 its own depop functions for alc_init and alc_shutup.
Assign it to ALC256 usage.

Signed-off-by: Kailang Yang <kailang@realtek.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>