dt-bindings: arm: renesas: Document iW-RainboW-G21D-Qseven-RZG1H board

Document the iW-RainboW-G21D-Qseven-RZG1H device tree bindings,
listing it as a supported board.
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Marian-Cristian Rotariu <marian-cristian.rotariu.rb@bp.renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1588542414-14826-9-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Documentation/devicetree/bindings/arm/renesas.yaml

@@ -59,6 +59,13 @@ properties:
               - iwave,g21m
           - const: renesas,r8a7742
 
+      - items:
+          - enum:
+              # iWave Systems RZ/G1H Qseven Development Platform (iW-RainboW-G21D-Qseven)
+              - iwave,g21d
+          - const: iwave,g21m
+          - const: renesas,r8a7742
+
       - description: RZ/G1M (R8A77430)
         items:
           - enum: