ALSA: hda - Check hard-wired DACs at first for ALC662 & co

Some Realtek codecs have the output pins hardwired with certain DACs.
These DACs have to be assigned at first and assign the rest for
multi-DAC pins so that all DACs can be assigned properly.

Without such an optimization, speaker outputs may be assigned to the
same DAC as the headphone or others.

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