ARM: shmobile: r8a7791 dtsi: Use "arm,gic-400" for GIC

Replace the "arm,cortex-a15-gic" compatible value for the GIC by
"arm,gic-400", as the R-Car Gen2 GIC is assumed to be a GIC-400.
This has been confirmed by reading the GICD_IIDR register, which reports
0x0200043b (GIC-400 = 0x02, ARM = 0x43b).

This has no effect on runtime behavior, as currently the GIC driver
treats both compatible values the same.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7791.dtsi

@@ -70,7 +70,7 @@ cpu1: cpu@1 {
 	};
 
 	gic: interrupt-controller@f1001000 {
-		compatible = "arm,cortex-a15-gic";
+		compatible = "arm,gic-400";
 		#interrupt-cells = <3>;
 		#address-cells = <0>;
 		interrupt-controller;