ARM: shmobile: sh73a0 dtsi: Add SoC-specific FSI2 compatible property

The FSI2 sound node 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>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/sh73a0.dtsi

@@ -317,7 +317,7 @@ pfc: pfc@e6050000 {
 
 	sh_fsi2: sound@ec230000 {
 		#sound-dai-cells = <1>;
-		compatible = "renesas,sh_fsi2";
+		compatible = "renesas,fsi2-sh73a0", "renesas,sh_fsi2";
 		reg = <0xec230000 0x400>;
 		interrupts = <0 146 0x4>;
 		status = "disabled";