ALSA: hda/realtek - Selectively call snd_hda_shutup_pins()

Instead of calling snd_hda_shutup_pins() unconditionally, allow it be
called in spec->shutup callback.  In this way, we can avoid calling
this function if it causes a problem like we see in the next patch
following this.

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