dt-bindings: mmc: renesas,sdhi: Add r8a774e1 support

Document SDHI controller for RZ/G2H (R8A774E1) SoC, which is compatible
with R-Car Gen3 SoC family.

Signed-off-by: Lad Prabhakar <[e-mail]>
Reviewed-by: Marian-Cristian Rotariu <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[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/renesas,sdhi.yaml

···
               - renesas,sdhi-r8a774a1 # RZ/G2M
               - renesas,sdhi-r8a774b1 # RZ/G2N
               - renesas,sdhi-r8a774c0 # RZ/G2E
+              - renesas,sdhi-r8a774e1 # RZ/G2H
               - renesas,sdhi-r8a7795  # R-Car H3
               - renesas,sdhi-r8a7796  # R-Car M3-W
               - renesas,sdhi-r8a77961 # R-Car M3-W+