spi: renesas,sh-msiof: Add r8a779g0 support

Document support for the Clock-Synchronized Serial Interface with FIFO
(MSIOF) in the Renesas R-Car V4H (R8A779G0) SoC.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Acked-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/a840c[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/spi/renesas,sh-msiof.yaml

···
           - enum:
               - renesas,msiof-r8a779a0      # R-Car V3U
               - renesas,msiof-r8a779f0      # R-Car S4-8
+              - renesas,msiof-r8a779g0      # R-Car V4H
           - const: renesas,rcar-gen4-msiof  # generic R-Car Gen4
                                             # compatible device
       - items: