board: rockchip: Add Radxa ROCK 4D

board: rockchip: Add Radxa ROCK 4D

The Radxa ROCK 4D is a compact single-board computer (SBC) featuring
numerous top-tier functions, features, and expansion options.

Equipped with the Rockchip RK3576 or RK3576J SoC, the ROCK 4D boasts an
octa-core CPU (4x Cortex-A72 + 4x Cortex-A53), Mali-G52 GPU, and a
powerful 6 TOPS NPU, making it ideal for AI and multimedia tasks.

Features tested on a Radxa ROCK 4D v1.112:
- SPI Flash boot
- Ethernet
- PCIe/NVMe
- USB host

ROCK 4D boards with SPI Flash is configured to boot from FSPI0->UFS->USB,
or directly from USB when the MASKROM button is pressed, booting
directly from SD-card is not possible on these boards.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>