ALSA: hda - Fix headset microphone detection for ASUS N551 and N751

ALSA: hda - Fix headset microphone detection for ASUS N551 and N751

Headset microphone does not work out of the box on ASUS Nx51
laptops. This patch fixes it.

Patch tested on Asus N551 laptop. Asus N751 part is not tested, but
according to [1] this laptop uses the same audiosystem.

1. https://bugzilla.kernel.org/show_bug.cgi?id=117781

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=195437
Signed-off-by: Mikhail Paulyshka <me@mixaill.tk>
Signed-off-by: Takashi Iwai <tiwai@suse.de>