ARM: dts: BCM5301X: Add interrupt properties to GPIO node

The GPIO controller is also an interrupt controller provider and is
currently missing the appropriate 'interrupt-controller' and
'#interrupt-cells' properties to denote that.

Fixes: fb026d3d ("ARM: BCM5301X: Add Broadcom's bus-axi to the DTS file")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

arch/arm/boot/dts/bcm5301x.dtsi

@@ -242,6 +242,8 @@ chipcommon: chipcommon@0 {
 
 			gpio-controller;
 			#gpio-cells = <2>;
+			interrupt-controller;
+			#interrupt-cells = <2>;
 		};
 
 		pcie0: pcie@12000 {