dt-bindings: serial: renesas,scif: Document r8a779a0 bindings

R-Car V3U (R8A779A0) SoC also has the R-Car Gen3 compatible
SCIF ports, so document the SoC specific bindings.

Signed-off-by: Yoshihiro Shimoda <[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: Greg Kroah-Hartman <[e-mail]>

Documentation/devicetree/bindings/serial/renesas,scif.yaml

···
               - renesas,scif-r8a77980     # R-Car V3H
               - renesas,scif-r8a77990     # R-Car E3
               - renesas,scif-r8a77995     # R-Car D3
+              - renesas,scif-r8a779a0     # R-Car V3U
           - const: renesas,rcar-gen3-scif # R-Car Gen3 and RZ/G2
           - const: renesas,scif           # generic SCIF compatible UART