dt-bindings: display: renesas,rzg2l-du: Document RZ/V2L DU bindings

Document DU found in RZ/V2L SoC. The DU block is identical to RZ/G2L
SoC and therefore use RZ/G2L fallback to avoid any driver changes.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20240218164840.57662-3-biju.das.jz@bp.renesas.comSigned-off-by: Maxime Ripard <mripard@kernel.org>

Documentation/devicetree/bindings/display/renesas,rzg2l-du.yaml

@@ -16,8 +16,13 @@ description: |
 
 properties:
   compatible:
-    enum:
-      - renesas,r9a07g044-du # RZ/G2{L,LC}
+    oneOf:
+      - enum:
+          - renesas,r9a07g044-du # RZ/G2{L,LC}
+      - items:
+          - enum:
+              - renesas,r9a07g054-du    # RZ/V2L
+          - const: renesas,r9a07g044-du # RZ/G2L fallback
 
   reg:
     maxItems: 1