ALSA: hda - Don't add channel suffix for headphone pin labels

The multiple headphone pins are usually handled as copied from the same
source, not as individual channels like front and surround.  Thus it'd
be more correct to avoid the channel suffix for "Headphone" pin labels
in snd_hda_get_pin_label() but give an index number instead.

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