ARM: dts: Enable Broadcom iProc mailbox controller

Reviewed-by: Jonathan Richardson <jonathan.richardson@broadcom.com>
Reviewed-by: Shreesha Rajashekar <shreesha.rajashekar@broadcom.com>
Reviewed-by: Ray Jui <ray.jui@broadcom.com>
Tested-by: Jonathan Richardson <jonathan.richardson@broadcom.com>
Reviewed-by: Vikram Prakash <vikram.prakash@broadcom.com>
Reviewed-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Jonathan Richardson <jonathan.richardson@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

arch/arm/boot/dts/bcm-cygnus.dtsi

@@ -114,6 +114,15 @@ pinctrl: pinctrl@0301d0c8 {
 			      <0x0301d24c 0x2c>;
 		};
 
+		mailbox: mailbox@03024024 {
+			compatible = "brcm,iproc-mailbox";
+			reg = <0x03024024 0x40>;
+			interrupts = <GIC_SPI 138 IRQ_TYPE_LEVEL_HIGH>;
+			#interrupt-cells = <1>;
+			interrupt-controller;
+			#mbox-cells = <1>;
+		};
+
 		gpio_crmu: gpio@03024800 {
 			compatible = "brcm,cygnus-crmu-gpio";
 			reg = <0x03024800 0x50>,