ALSA: hda - Fix stac92hd83xxx_amp_nids[]

Fix the bug introduced in commit c15c5060:
  sound/pci/hda/patch_sigmatel.c: In function ‘patch_stac92hd83xxx’:
  sound/pci/hda/patch_sigmatel.c:4765: warning: assignment from incompatible pointer type

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