dt-bindings: mmc: renesas,sdhi: Document R-Car S4-8 and generic Gen4 support

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20220603233810.21972-1-wsa+renesas@sang-engineering.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

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

@@ -61,6 +61,10 @@ properties:
               - renesas,sdhi-r9a07g044 # RZ/G2{L,LC}
               - renesas,sdhi-r9a07g054 # RZ/V2L
           - const: renesas,rcar-gen3-sdhi # R-Car Gen3 or RZ/G2
+      - items:
+          - enum:
+              - renesas,sdhi-r8a779f0  # R-Car S4-8
+          - const: renesas,rcar-gen4-sdhi # R-Car Gen4
 
   reg:
     maxItems: 1