dt-bindings: arm: rockchip: Add Protonic MECSBC board

MECSBC is a single board computer for blood analysis machines from
RR-Mechatronics, designed and manufactured by Protonic Holland, based on
the Rockchip RK3568 SoC.
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Link: https://lore.kernel.org/r/20240405-protonic-mecsbc-v2-1-0a6fedc78b9f@pengutronix.deSigned-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -700,6 +700,11 @@ properties:
               - powkiddy,x55
           - const: rockchip,rk3566
 
+      - description: Protonic MECSBC board
+        items:
+          - const: prt,mecsbc
+          - const: rockchip,rk3568
+
       - description: QNAP TS-433-4G 4-Bay NAS
         items:
           - const: qnap,ts433