ALSA: hda - Fix hp-mic mode without VREF bits

commit 16c0cefe8951b2c4b824fd06011ac1b359b1ab3b upstream.

When the hp mic pin has no VREF bits, the driver forgot to set PIN_IN
bit.  Spotted during debugging old MacBook Airs.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=65681


Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>