arm64: dts: renesas: r8a774c0: Clean up CPU compatibles

Apparently this DTS crossed over with commit 31af04cd ("arm64: dts:
Remove inconsistent use of 'arm,armv8' compatible string") and missed
out on the cleanup, so put it right.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a774c0.dtsi

@@ -70,7 +70,7 @@ cpus {
 		#size-cells = <0>;
 
 		a53_0: cpu@0 {
-			compatible = "arm,cortex-a53", "arm,armv8";
+			compatible = "arm,cortex-a53";
 			reg = <0>;
 			device_type = "cpu";
 			power-domains = <&sysc R8A774C0_PD_CA53_CPU0>;
@@ -81,7 +81,7 @@ a53_0: cpu@0 {
 		};
 
 		a53_1: cpu@1 {
-			compatible = "arm,cortex-a53", "arm,armv8";
+			compatible = "arm,cortex-a53";
 			reg = <1>;
 			device_type = "cpu";
 			power-domains = <&sysc R8A774C0_PD_CA53_CPU1>;