drm: nouveau: lsfw: cleanup coccinelle warning

odd_ptr_err.cocci has complained about this warning for a long time:
lsfw.c:194:5-11: inconsistent IS_ERR and PTR_ERR on line 195.

Although there is no actual impact, it can improve scanning efficiency.

Signed-off-by: Wang Qing <wangqing@vivo.com>

drivers/gpu/drm/nouveau/nvkm/subdev/acr/lsfw.c

@@ -191,7 +191,8 @@ nvkm_acr_lsfw_load_bl_inst_data_sig(struct nvkm_subdev *subdev,
 	u32 *bldata;
 	int ret;
 
-	if (IS_ERR((lsfw = nvkm_acr_lsfw_add(func, acr, falcon, id))))
+	lsfw = nvkm_acr_lsfw_add(func, acr, falcon, id);
+	if (IS_ERR(lsfw)
 		return PTR_ERR(lsfw);
 
 	ret = nvkm_firmware_load_name(subdev, path, "bl", ver, &bl);