ALSA: hda - Return "Headphone Mic" from hda_get_autocfg_input_label()

Instead of handling special cases in the caller side, give a proper
name string "Headphone Mic" from hda_get_autocfg_input_label() when
the headhpone jack pin is specified as an input.

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