system-arm: Add ITS node in platforms/vexpress_gem5_v2_base.dtsi

This is aligning sources with DTB autogeneration

Change-Id: Icf369eb85719c91da770398b45645d8b03d8abf3
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20982
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/system/arm/dt/platforms/vexpress_gem5_v2_base.dtsi b/system/arm/dt/platforms/vexpress_gem5_v2_base.dtsi
index 3340740..eba0db2 100644
--- a/system/arm/dt/platforms/vexpress_gem5_v2_base.dtsi
+++ b/system/arm/dt/platforms/vexpress_gem5_v2_base.dtsi
@@ -49,6 +49,13 @@
 		#size-cells = <0x2>;
 		linux,phandle = <0x1>;
 		phandle = <0x1>;
+
+		gic-its@2e010000 {
+			compatible = "arm,gic-v3-its";
+			msi-controller;
+			#msi-cells = <1>;
+			reg = <0x0 0x2e010000 0 0x20000>;
+		};
 	};
 
 	timer {