riscv: dts: starfive: Add cpu scaling for JH7110 SoC

Add the operating-points-v2 to support cpu scaling on StarFive JH7110 SoC.
It supports up to 4 cpu frequency loads.

Signed-off-by: Mason Huo <mason.huo@starfivetech.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>