ARM: tegra: Add GIC for Tegra30

Add a device tree node for the GIC found on Tegra30. U-Boot doesn't use
it directly but subsequent patches will add device tree nodes that
reference it by phandle.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

arch/arm/dts/tegra30.dtsi

@@ -6,6 +6,15 @@
 
 / {
 	compatible = "nvidia,tegra30";
+	interrupt-parent = <&intc>;
+
+	intc: interrupt-controller@50041000 {
+		compatible = "arm,cortex-a9-gic";
+		reg = <0x50041000 0x1000
+		       0x50040100 0x0100>;
+		interrupt-controller;
+		#interrupt-cells = <3>;
+	};
 
 	tegra_car: clock {
 		compatible = "nvidia,tegra30-car";