rockchip: add Radxa E25 board support

rockchip: add Radxa E25 board support

Radxa E25 is a network application carrier board for the Radxa CM3
Industrial (CM3I) SoM, which is based on the Rockchip RK3568 SoC.

It has the following features:

- MicroSD card socket, on board eMMC flash
- 2x 2.5GbE Realtek RTL8125B Ethernet transceiver
- 1x USB Type-C port (Power and Serial console)
- 1x USB 3.0 OTG port
- mini PCIe socket (USB or PCIe)
- ngff PCIe socket (USB or SATA)
- 1x User LED and 16x RGB LEDs
- 26-pin expansion header

Installation:
Uncompress the OpenWrt sysupgrade and write it to a micro SD card or
internal eMMC using dd.

Signed-off-by: Marius Durbaca <mariusd84@gmail.com>