ALSA: hda/realtek - Disable headset Mic VREF for headset mode of ALC225

commit d1dd42110d2727e81b9265841a62bc84c454c3a2 upstream.

Disable Headset Mic VREF for headset mode of ALC225.
This will be controlled by coef bits of headset mode functions.

[ Fixed a compile warning and code simplification -- tiwai ]

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>