ARM: shmobile: r8a73a4 dtsi: Add SoC-specific irqc compatible property

The interrupt controller used the generic compatible property only.
Add the SoC-specific one, to make it future proof.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a73a4.dtsi

@@ -51,7 +51,7 @@ timer {
 	};
 
 	irqc0: interrupt-controller@e61c0000 {
-		compatible = "renesas,irqc";
+		compatible = "renesas,irqc-r8a73a4", "renesas,irqc";
 		#interrupt-cells = <2>;
 		interrupt-controller;
 		reg = <0 0xe61c0000 0 0x200>;
@@ -90,7 +90,7 @@ irqc0: interrupt-controller@e61c0000 {
 	};
 
 	irqc1: interrupt-controller@e61c0200 {
-		compatible = "renesas,irqc";
+		compatible = "renesas,irqc-r8a73a4", "renesas,irqc";
 		#interrupt-cells = <2>;
 		interrupt-controller;
 		reg = <0 0xe61c0200 0 0x200>;