ALSA: hda - Fix HP/line-out initialization with IDT/STAC codecs

It's possible that hp_detect is set even though no headphone pin is
detected.  The driver issues, however, an unsol event only to hp_pins[0],
which can be invalid.

This patch adds the check of the valid pin to send an unsol event
at initialization and resume callbacks.

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