arm: mach-rockchip: bind sub-nodes for rk3399_syscon

There are some sub-nodes under the grf DT, so add bind callback
function in rk3399 syscon driver to scan them recursively.

Signed-off-by: Frank Wang <frank.wang@rock-chips.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com> # roc-rk3399-pc
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>

arch/arm/mach-rockchip/rk3399/syscon_rk3399.c

@@ -21,6 +21,9 @@ static const struct udevice_id rk3399_syscon_ids[] = {
 U_BOOT_DRIVER(syscon_rk3399) = {
 	.name = "rk3399_syscon",
 	.id = UCLASS_SYSCON,
+#if !CONFIG_IS_ENABLED(OF_PLATDATA)
+	.bind = dm_scan_fdt_dev,
+#endif
 	.of_match = rk3399_syscon_ids,
 };