[ALSA] fix multi-channel for model==full

HDA Codec driver
The patch_cm9880.c can't play side/C/B channels from front panel jacks.
I fixed it by adding select pin.

Signed-off-by: ChenLi Tien <cltien@cmedia.com.tw>
Signed-off-by: Takashi Iwai <tiwai@suse.de>