ALSA: hda - Fix parsing of CMI8888 codec

CMI8888 codec chip has a boost amp (only) on the headphone pin, and
this confuses the generic parser, which tends to pick up the most
outside amp.  This results in the wrong volume setup, as the driver
complains like:
  hda_codec: Mismatching dB step for vmaster slave (-100!=1000)

For avoiding this problem, rule out the amp on NID 0x10 and create
"Headphone Amp" volume control manually instead.

Note that this patch still doesn't fix all problems yet.  The sound
output from the line out seems still too low.  It will be fixed in
another patch (hopefully).

Reported-and-tested-by: Vincent Lejeune <vljn@ovi.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>