rockchip: add support for Radxa ROCK 5T

rockchip: add support for Radxa ROCK 5T

The Radxa ROCK 5T is a single board computer using the Rockchip
RK3588(J) SoC.

- https://radxa.com/products/rock5/5t

Hardware
--------

- Quad Cortex-A76 and Quad Cortex-A55 CPU
- Mali-G610 MP4 GPU
- 6 TOPS NPU
- 4/8/16/24/32GB LPDDR5 RAM
- 16/32/64/128/256GB on-board eMMC (optional)
- 16MB SPI NOR flash
- microSD card slot
- Wi-Fi 6E (Intel AX210, limited support)
- 2x 2.5 Gigabit Ethernet ports with PoE (additional PoE module required)
- USB 3.1 Gen1 Type-C HOST/OTG port
- 2x USB 3.1 Gen1 Type-A HOST ports
- 2x USB 2.0 Type-A HOST ports
- 2x M.2 M Key connectors with PCIe 3.0 x2
- M.2 B Key connector
- SIM card slot
- RTC battery connector
- PWM fan connector
- 20x2 pin header
- 5525 12V DC jack

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>