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=195437Signed-off-by: NMikhail Paulyshka <me@mixaill.tk>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>