rockchip: rk3328: fix syscon id table

syscon id table need a dummy member as NULL ending, or else system
will panic while try to match a compatible in this table as a list.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

arch/arm/mach-rockchip/rk3328/syscon_rk3328.c

@@ -11,6 +11,7 @@
 
 static const struct udevice_id rk3328_syscon_ids[] = {
 	{ .compatible = "rockchip,rk3328-grf", .data = ROCKCHIP_SYSCON_GRF },
+	{ }
 };
 
 U_BOOT_DRIVER(syscon_rk3328) = {