ALSA: hda: alc883 model for ASUS P5Q-EM boards

Add a new alc883 model ALC1200_ASUS_P5Q for ASUS P5Q-EM boards.
It is the same as ALC883_6ST_DIG except that the SPDIF digital
output nid is 0x10.

Tested-by: Andrei Tanas <andrei@tanas.ca>
Signed-off-by: Wu Fengguang <wfg@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>