ALSA: hda - Fix jack gating when auto_{mute,mic} is suppressed.

The snd_hda_jack_set_gating_jack() call didn't work when
auto_{mute,mic} is suppressed because (1) am_entry is
not filled with nid of the mic pin. (2) The jacks are not
created (by snd_hda_jack_detect_enable_callback) before the
snd_hda_jack_set_gating_jack call.

Now we use the first input pin nid directly, and create the jack if it
doesn't exist yet.

Signed-off-by: Chih-Chung Chang <chihchung@chromium.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>