ALSA: hda - Constify some API function arguments

Also fixed the assignment of multiout.dac_nids to satisfy const.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/hda/patch_analog.c b/sound/pci/hda/patch_analog.c
index 1231748..6df9943 100644
--- a/sound/pci/hda/patch_analog.c
+++ b/sound/pci/hda/patch_analog.c
@@ -2845,7 +2845,7 @@
 	/* check the pins hardwired to audio widget */
 	for (i = 0; i < cfg->line_outs; i++) {
 		idx = ad1988_pin_idx(cfg->line_out_pins[i]);
-		spec->multiout.dac_nids[i] = ad1988_idx_to_dac(codec, idx);
+		spec->private_dac_nids[i] = ad1988_idx_to_dac(codec, idx);
 	}
 	spec->multiout.num_dacs = cfg->line_outs;
 	return 0;