arm64: dts: renesas: r8a779g0: Add Cortex-A76 1.8 GHz opp

Add an operating point for running the Cortex-A76 CPU cores on R-Car
V4H at 1.8 GHz (High Performance mode).

Based on a patch in the BSP by Tho Vu.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/cc2bae27776523f499d01655ef18fe463a3ae1ae.1670492384.git.geert+renesas@glider.be

arch/arm64/boot/dts/renesas/r8a779g0.dtsi

@@ -39,6 +39,12 @@ opp-1700000000 {
 			clock-latency-ns = <500000>;
 			opp-suspend;
 		};
+		opp-1800000000 {
+			opp-hz = /bits/ 64 <1800000000>;
+			opp-microvolt = <880000>;
+			clock-latency-ns = <500000>;
+			turbo-mode;
+		};
 	};
 
 	cpus {