ALSA: hda - Add support for multiple headphone/speaker controls for Realtek

So far, Realtek auto-parser assumed that the multiple pins are only for
line-outs, and assigned the channel names like Front, Surround, etc for
the multiple outputs.  But, there are devices that have multiple
headphones, and these can be better controlled with the corresponding
control-name like "Headphone" with indicies.

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