dt-bindings: arm: rockchip: Add Asus Tinker Board 3/3S

dt-bindings: arm: rockchip: Add Asus Tinker Board 3/3S

Document the compatible strings for Asus Tinker Board 3 [1] and 3S [2],
which are SBCs based on the Rockchip 3566 SoC.

The "3S" version ("S" for "storage") just adds a 16 GB eMMC
and a "mask ROM" DIP switch to the "3" version.

[1] https://tinker-board.asus.com/series/tinker-board-3.html
[2] https://tinker-board.asus.com/series/tinker-board-3s.html

Signed-off-by: Michael Opdenacker <michael.opdenacker@rootcommit.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://patch.msgid.link/20251118-tinker3-v3-1-2903693f2ebb@rootcommit.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>