rockchip: add support for Radxa ROCK Pi E v3.0

rockchip: add support for Radxa ROCK Pi E v3.0

Radxa ROCK Pi E v3.0 is a compact networking SBC[1] using the Rockchip
RK3328 SoC.

Hardware
--------
- Rockchip RK3328 SoC
- Quad A53 CPU
- 512MB/1GB/2GB DDR4 RAM
- 4/8/16/32GB eMMC
- Micro SD Card slot
- WiFi 4 and BT 4, or WiFi 5 and BT 5 (not supported yet)
- 1x 1000M Ethernet with PoE support (additional PoE HAT required)
- 1x 100M Ethernet
- 1x USB 3.0 Type-A port (Host)
- 1x 4-ring 3.5mm headphone jack
- 40 Pin GPIO header

[1] https://radxa.com/products/rockpi/pie

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

Signed-off-by: FUKAUMI Naoki <naoki@radxa.com>
Link: https://github.com/openwrt/openwrt/pull/15984
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>