ALSA: hda - Fix wrong arguments for path deactivation checks

The arguments to call is_active_nid() in activate_amp() were swapped,
and this resulted in the muted amp on some SPDIF output pins.

Also, the index to be passed to is_active_nid() must be idx_to_check.
Otherwise it checks the wrong connection in the case of implicit aamix
connection paths.

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