dt-bindings: serial: renesas,scif: Document r8a779g0 support

Document support for the Serial Communication Interface with FIFO (SCIF)
in the Renesas R-Car V4H (R8A779G0) SoC.

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/8a2d04651f04a97d652395b4d933af5c3c8d5b5b.1666360789.git.geert+renesas@glider.be


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>