dt-bindings: mmc: renesas,sdhi: Add R-Car Gen4 clock requirements

The patch enabling generic Gen4 support forgot to add the clock
requirements which are the same as for Gen3. Update the binding.
Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20220608122344.3431-1-wsa+renesas@sang-engineering.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml

@@ -145,6 +145,7 @@ allOf:
               enum:
                 - renesas,rcar-gen2-sdhi
                 - renesas,rcar-gen3-sdhi
+                - renesas,rcar-gen4-sdhi
       then:
         properties:
           clocks: