arm64: dts: fvp: Fix ITS node names and #msi-cells

The GIC ITS nodes in the fastmodel DTS files were not fully binding
compliant.

Use one of the allowed node names, also add the required #msi-cells
property for the older model.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Andre Przywara <[email protected]>
Signed-off-by: Sudeep Holla <[email protected]>

Author: Andre-ARM

arch/arm64/boot/dts/arm/foundation-v8-gicv3.dtsi

@@ -19,9 +19,10 @@
 			<0x0 0x2c02f000 0x0 0x2000>;
 		interrupts = <GIC_PPI 9 IRQ_TYPE_LEVEL_HIGH>;
 
-		its: its@2f020000 {
+		its: msi-controller@2f020000 {
 			compatible = "arm,gic-v3-its";
 			msi-controller;
+			#msi-cells = <1>;
 			reg = <0x20000 0x20000>;
 		};
 	};

arch/arm64/boot/dts/arm/fvp-base-revc.dts

@@ -126,7 +126,7 @@
 		      <0x0 0x2c02f000 0 0x2000>;	// GICV
 		interrupts = <GIC_PPI 9 IRQ_TYPE_LEVEL_HIGH>;
 
-		its: its@2f020000 {
+		its: msi-controller@2f020000 {
 			#msi-cells = <1>;
 			compatible = "arm,gic-v3-its";
 			reg = <0x0 0x2f020000 0x0 0x20000>; // GITS