ARM: dts: rockchip: Add Onion Omega4 Evaluation Board

ARM: dts: rockchip: Add Onion Omega4 Evaluation Board

The Onion Omega4 Evaluation Board is based on the RV1103B SoC and has:

 - 256 MB of RAM
 - 256 MB of SPI-NAND
 - Ethernet
 - USB OTG
 - Wifi
 - SD card
 - Camera connector

The details can be found at:
https://documentation.onioniot.com/omega4/getting-started/

Add the initial support for this board so that it can fully boot into
Linux with the root file system stored in the SPI NAND.

Signed-off-by: Fabio Estevam <festevam@nabladev.com>
Link: https://patch.msgid.link/20260313131058.708361-4-festevam@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>