ALSA: hda/generic - Fix wrong initial power state for fixed pins

When the widget power-saving is enabled, the first automute hook
invocation checks through the whole pins and it also tries to
synchronize the power state.  However, this results in a wrong state
because it calls unconditionally snd_hda_jack_detect_state().
This patch adds a check of jack detectability before the actual jack
detection call.

Signed-off-by: Takashi Iwai <tiwai@suse.de>