dt-bindings: renesas,rcar-dmac: Add r8a779g0 support

Document support for the Direct Memory Access Controllers (DMAC) in the
Renesas R-Car V4H (R8A779G0) SoC.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/0a4d40092a51345003742725aea512a815d27e89.1664204526.git.geert+renesas@glider.be


Signed-off-by: Vinod Koul <vkoul@kernel.org>