rockchip: add support for Radxa E52C

rockchip: add support for Radxa E52C

The Radxa E52C is a compact network computer using the Rockchip RK3582
SoC.

- https://radxa.com/products/network-computer/e52c

Hardware
--------

- Dual Cortex-A76 and Quad Cortex-A55 CPU
- 5 TOPS NPU
- 2/4/8GB LPDDR4 RAM
- 16/32/64GB on-board eMMC
- microSD card slot
- 2x 2.5 Gigabit Ethernet ports
- USB 3.1 Gen1 Type-A HOST/OTG port
- USB Type-C debug port
- USB Type-C power port

Installation
------------

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

Signed-off-by: FUKAUMI Naoki <naoki@radxa.com>
Link: https://github.com/openwrt/openwrt/pull/19867
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>