dt-bindings: renesas,rcar-dmac: R-Car V3U is R-Car Gen4

Despite the name, R-Car V3U is the first member of the R-Car Gen4
family. Hence move its compatible value to the R-Car Gen4 section.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Acked-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/e6e4c[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

Documentation/devicetree/bindings/dma/renesas,rcar-dmac.yaml

···
           - const: renesas,rcar-dmac
 
       - items:
-          - const: renesas,dmac-r8a779a0 # R-Car V3U
-
-      - items:
-          - const: renesas,dmac-r8a779f0 # R-Car S4-8
-          - const: renesas,rcar-gen4-dmac
+          - enum:
+              - renesas,dmac-r8a779a0     # R-Car V3U
+              - renesas,dmac-r8a779f0     # R-Car S4-8
+          - const: renesas,rcar-gen4-dmac # R-Car Gen4
 
   reg: true
 
···
     compatible:
       contains:
         enum:
-          - renesas,dmac-r8a779a0
           - renesas,rcar-gen4-dmac
 then:
   properties: