riscv: dts: starfive: jh7110: Add ethernet device nodes

Add JH7110 ethernet device node to support gmac driver for the JH7110
RISC-V SoC.

Tested-by: Tommaso Merciai <tomm.merciai@gmail.com>
Signed-off-by: Yanhong Wang <yanhong.wang@starfivetech.com>
Signed-off-by: Samin Guo <samin.guo@starfivetech.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>