Specficy subdevice 0 for front/surround* of HDA-Intel.conf

The subdevice 0 is used for multi-channel outputs.
This fixes the detection of multi-channel devices of VIA codecs
by PulseAudio.

Reported-by: Raymond Yau <superquad.vortex2@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>