arm64: dts: renesas: r8a77990: Add dynamic power coefficient

Describe the dynamic power coefficient of A53 CPUs.

Based on work by Gaku Inami <gaku.inami.xw@bp.renesas.com> and others.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a77990.dtsi

@@ -88,6 +88,7 @@ a53_0: cpu@0 {
 			power-domains = <&sysc R8A77990_PD_CA53_CPU0>;
 			next-level-cache = <&L2_CA53>;
 			enable-method = "psci";
+			dynamic-power-coefficient = <277>;
 			clocks =<&cpg CPG_CORE R8A77990_CLK_Z2>;
 			operating-points-v2 = <&cluster1_opp>;
 		};