ARM: shmobile: r7s72100 dtsi: Use "arm,pl390" for GIC

Replace the "arm,cortex-a9-gic" compatible value for the GIC by
"arm,pl390", as the documentation states it is a PL390.
This has been confirmed (thanks Chris, Wolfram!) by reading the
GICD_IIDR register, which reports 0x0000043b (PL390 = 0x00, 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/r7s72100.dtsi

@@ -329,7 +329,7 @@ spi4: spi@e800e800 {
 	};
 
 	gic: interrupt-controller@e8201000 {
-		compatible = "arm,cortex-a9-gic";
+		compatible = "arm,pl390";
 		#interrupt-cells = <3>;
 		#address-cells = <0>;
 		interrupt-controller;