arm64: dts: rockchip: add ROCK 5 ITX board

arm64: dts: rockchip: add ROCK 5 ITX board

The ROCK 5 ITX as the name suggests is made in the ITX form factor and
actually built in a form to be used in a regular case even providing
connectors for regular front-panel io.

It can be powered either by 12V, ATX power-supply or PoE.

Notable peripherals are the 4 SATA ports, M.2 M-Key slot, M.2 E-key slot,
2*2.5Gb PCIe-connected Ethernet NICs.

As of yet unsupported display options consist of 2*HDMI, DP via USB-c,
eDP + 2*DSI via PCB connectors.

USB ports are 4*USB3 + 2*USB2 on the back panel and 2-port front-panel
connector.

Schematics for the board can be found on
- https://dl.radxa.com/rock5/5itx/radxa_rock_5_itx_X1100_schematic.pdf
- https://dl.radxa.com/rock5/5itx/v1110/radxa_rock_5itx_v1110_schematic.pdf

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20240704153815.837392-3-heiko@sntech.de