ARM: dts: tango4: remove bogus interrupt-controller property

dtc points out that the parent node of the interrupt controllers is not
actually an interrupt controller itself, and lacks an #interrupt-cells
property:

arch/arm/boot/dts/tango4-vantage-1172.dtb: Warning (interrupts_property): Missing #interrupt-cells in interrupt-parent /soc/interrupt-controller@6e000

This removes the annotation.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/boot/dts/tango4-common.dtsi

@@ -156,7 +156,6 @@ intc: interrupt-controller@6e000 {
 			reg = <0x6e000 0x400>;
 			ranges = <0 0x6e000 0x400>;
 			interrupt-parent = <&gic>;
-			interrupt-controller;
 			#address-cells = <1>;
 			#size-cells = <1>;