arm64: dts: rockchip: disable mailbox of RK3368 SoCs per default

Default to disable mailbox in rk3368 core dts file.
Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3368.dtsi

@@ -640,6 +640,7 @@ mbox: mbox@ff6b0000 {
 		clocks = <&cru PCLK_MAILBOX>;
 		clock-names = "pclk_mailbox";
 		#mbox-cells = <1>;
+		status = "disabled";
 	};
 
 	pmugrf: syscon@ff738000 {