ARM: BCM5301X: Add Broadcom's bus-axi to the DTS file

This has been successfully tested on Netgear R6250 and two other
development (unnamed) devices, all of them BCM4708 based.
We also got a possitive feedback from R7000 (BCM4709) tester.
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

arch/arm/boot/dts/bcm5301x.dtsi

@@ -8,6 +8,7 @@
  * Licensed under the GNU/GPL. See COPYING for details.
  */
 
+#include <dt-bindings/gpio/gpio.h>
 #include <dt-bindings/interrupt-controller/irq.h>
 #include <dt-bindings/interrupt-controller/arm-gic.h>
 #include "skeleton.dtsi"
@@ -92,4 +93,19 @@ clk_periph: periph {
 			clock-frequency = <400000000>;
 		};
 	};
+
+	axi@18000000 {
+		compatible = "brcm,bus-axi";
+		reg = <0x18000000 0x1000>;
+		ranges = <0x00000000 0x18000000 0x00100000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		chipcommon: chipcommon@0 {
+			reg = <0x00000000 0x1000>;
+
+			gpio-controller;
+			#gpio-cells = <2>;
+		};
+	};
 };