dt-bindings: mmc: rockchip-dw-mshc: Add Rockchip RK1808

Add a compatible string for Rockchip RK1808 SoC.
Signed-off-by: Andreas Färber <afaerber@suse.de>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210516230551.12469-7-afaerber@suse.deSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.yaml

@@ -30,6 +30,7 @@ properties:
       - items:
           - enum:
               - rockchip,px30-dw-mshc
+              - rockchip,rk1808-dw-mshc
               - rockchip,rk3036-dw-mshc
               - rockchip,rk3228-dw-mshc
               - rockchip,rk3308-dw-mshc