arm64: dts: apm: mailbox device tree node for APM X-Gene platform.

Mailbox device tree node for APM X-Gene platform.
Signed-off-by: Feng Kan <fkan@apm.com>
Signed-off-by: Duc Dang <dhdang@apm.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

arch/arm64/boot/dts/apm/apm-storm.dtsi

@@ -691,6 +691,20 @@ pcie4: pcie@1f510000 {
 			msi-parent = <&msi>;
 		};
 
+		mailbox: mailbox@10540000 {
+			compatible = "apm,xgene-slimpro-mbox";
+			reg = <0x0 0x10540000 0x0 0xa000>;
+			#mbox-cells = <1>;
+			interrupts =    <0x0 0x0 0x4>,
+					<0x0 0x1 0x4>,
+					<0x0 0x2 0x4>,
+					<0x0 0x3 0x4>,
+					<0x0 0x4 0x4>,
+					<0x0 0x5 0x4>,
+					<0x0 0x6 0x4>,
+					<0x0 0x7 0x4>;
+		};
+
 		serial0: serial@1c020000 {
 			status = "disabled";
 			device_type = "serial";