The front mic jack (pink color) can't detect any plug or unplug. After
applying this fix, both detecting function and recording function
work well.

BugLink: https://bugs.launchpad.net/bugs/1564712
Cc: stable@vger.kernel.org
Signed-off-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>