ARM64: zynqmp: Add interrupt-controller property to gpio nodes

GPIO driver supports an input interrupt that's why gpio node itself can
be labeled as interrupt controller.

Reported-by: John Linn <linnj@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/arm/dts/zynqmp.dtsi

@@ -581,6 +581,8 @@
 			compatible = "xlnx,zynqmp-gpio-1.0";
 			status = "disabled";
 			#gpio-cells = <0x2>;
+			#interrupt-cells = <2>;
+			interrupt-controller;
 			interrupt-parent = <&gic>;
 			interrupts = <0 16 4>;
 			reg = <0x0 0xff0a0000 0x1000>;