[ALSA] choose multi-channel jacks automatically

HDA Codec driver
Patch by C.L. Tien <cltien@cmedia.com.tw>:

The patch makes cm9880 to choose multi-channel jacks automatically.

1. I found the current code has basic_init, which already includes
   necessary controls for 6-stack initialization, so I don't need
   another model.

2. I add a new model 'auto' to let the driver find a. if there are
   option real panel/front panel, b. the jacks to be used for multichannel.

Because the jack color are based on MS's channel sequence, so the 'auto'
model will pick the same jacks for multichannel MS uses. I did this to
hope to minimize users questions. These code can also be applied to other
codecs but I don't have any to test.

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