arm64: dts: allwinner: h6: Add msgbox node

The H6 SoC contains a message box that can be used to send messages and
interrupts back and forth between the ARM application CPUs and the ARISC
coprocessor. Add a device tree node for it.
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>

arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi

@@ -231,6 +231,16 @@ dma: dma-controller@3002000 {
 			#dma-cells = <1>;
 		};
 
+		msgbox: mailbox@3003000 {
+			compatible = "allwinner,sun50i-h6-msgbox",
+				     "allwinner,sun6i-a31-msgbox";
+			reg = <0x03003000 0x1000>;
+			clocks = <&ccu CLK_BUS_MSGBOX>;
+			resets = <&ccu RST_BUS_MSGBOX>;
+			interrupts = <GIC_SPI 44 IRQ_TYPE_LEVEL_HIGH>;
+			#mbox-cells = <1>;
+		};
+
 		sid: efuse@3006000 {
 			compatible = "allwinner,sun50i-h6-sid";
 			reg = <0x03006000 0x400>;