arm64: dts: rockchip: Enable Ethernet controller on Radxa E20C

The Radxa E20C has two GbE ports, LAN and WAN. The LAN port is provided
using a GMAC controller and a YT8531C PHY and the WAN port is provided
by an RTL8111H PCIe Ethernet controller.

Enable support for the LAN port on Radxa E20C.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Tested-by: Yao Zi <ziyao@disroot.org>
Link: https://lore.kernel.org/r/20250509202402.260038-3-jonas@kwiboo.se


Signed-off-by: Heiko Stuebner <heiko@sntech.de>