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

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: dd7188eb4ed128dc ("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