HP Z1 Gen3 AiO with Conexant codec doesn't give an unsolicited event
to the headset mic pin upon the jack plugging, it reports only to the
headphone pin.  It results in the missing mic switching.  Let's fix up
by simply gating the jack event.

Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>