arm64: dts: renesas: r8a77990: Remove bogus voltages from OPP table

According to the R-Car Series, 3rd Generation Hardware User’s Manual
Rev. 2.30, the System CPU cores on R-Car E3 do not have their own power
supply, but use the common internal power supply (typical 1.03V).

Hence remove the "opp-microvolt" properties from the Operating
Performance Points table.  They are optional, and unused, when none of
the CPU nodes is tied to a regulator using the "cpu-supply" property.

Fixes: dd7188eb ("arm64: dts: renesas: r8a77990: Add OPPs table for cpu devices")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/9232578d9d395d529f64db3333a371e31327f459.1676560856.git.geert+renesas@glider.be

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

@@ -49,17 +49,14 @@ cluster1_opp: opp-table-1 {
 		opp-shared;
 		opp-800000000 {
 			opp-hz = /bits/ 64 <800000000>;
-			opp-microvolt = <820000>;
 			clock-latency-ns = <300000>;
 		};
 		opp-1000000000 {
 			opp-hz = /bits/ 64 <1000000000>;
-			opp-microvolt = <820000>;
 			clock-latency-ns = <300000>;
 		};
 		opp-1200000000 {
 			opp-hz = /bits/ 64 <1200000000>;
-			opp-microvolt = <820000>;
 			clock-latency-ns = <300000>;
 			opp-suspend;
 		};