dt-bindings: mmc: rockchip-dw-mshc: Document Rockchip RV1126

Add a compatible string for Rockchip RV1126 SoC.

Signed-off-by: Jagan Teki <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Ulf Hansson <[e-mail]>

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

···
               - rockchip,rk3399-dw-mshc
               - rockchip,rk3568-dw-mshc
               - rockchip,rv1108-dw-mshc
+              - rockchip,rv1126-dw-mshc
           - const: rockchip,rk3288-dw-mshc
 
   reg: