drm: rcar-du: Fix memory leak in rcar_du_vsps_init()

The rcar_du_vsps_init() doesn't free the np allocated by
of_parse_phandle_with_fixed_args() for the non-error case.

Fix memory leak for the non-error case.

While at it, replace the label 'error'->'done' as it applies to non-error
case as well and update the error check condition for rcar_du_vsp_init()
to avoid breakage in future, if it returns positive value.

Fixes: 3e81374e2014 ("drm: rcar-du: Support multiple sources from the same VSP")
Signed-off-by: Biju Das <[e-mail]>
Reviewed-by: Laurent Pinchart <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Tomi Valkeinen <[e-mail]>

drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c

···
 		ret = of_parse_phandle_with_fixed_args(np, vsps_prop_name,
 						       cells, i, &args);
 		if (ret < 0)
-			goto error;
+			goto done;
 
 		/*
 		 * Add the VSP to the list or update the corresponding existing
···
 		vsp->dev = rcdu;
 
 		ret = rcar_du_vsp_init(vsp, vsps[i].np, vsps[i].crtcs_mask);
-		if (ret < 0)
-			goto error;
+		if (ret)
+			goto done;
 	}
 
-	return 0;
-
-error:
+done:
 	for (i = 0; i < ARRAY_SIZE(vsps); ++i)
 		of_node_put(vsps[i].np);