dt-bindings: arm: rockchip: add Radxa ROCK 5C

Add devicetree binding for the Radxa ROCK 5C.

Radxa ROCK 5C is a 8K computer for everything[1] using the Rockchip
RK3588S2 chip.

[1] https://radxa.com/products/rock5/5c

Signed-off-by: FUKAUMI Naoki <naoki@radxa.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20241021090548.1052-1-naoki@radxa.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Author: RadxaNaoki

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -895,6 +895,11 @@ properties:
           - const: radxa,rock-5b
           - const: rockchip,rk3588
 
+      - description: Radxa ROCK 5C
+        items:
+          - const: radxa,rock-5c
+          - const: rockchip,rk3588s
+
       - description: Radxa ROCK S0
         items:
           - const: radxa,rock-s0