ARM: kirkwood: fix missing #interrupt-cells property

The gpio controller on kirkwood can provide interrupts but is missing
the #interrupt-cells property. This patch just adds it to both gpio
controllers.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

arch/arm/boot/dts/kirkwood.dtsi

@@ -36,6 +36,7 @@
 			reg = <0x10100 0x40>;
 			ngpios = <32>;
 			interrupt-controller;
+			#interrupt-cells = <2>;
 			interrupts = <35>, <36>, <37>, <38>;
 		};
 
@@ -46,6 +47,7 @@
 			reg = <0x10140 0x40>;
 			ngpios = <18>;
 			interrupt-controller;
+			#interrupt-cells = <2>;
 			interrupts = <39>, <40>, <41>;
 		};