dt-bindings: dma: rz-dmac: Document RZ/V2L SoC

Document RZ/V2L DMAC bindings. RZ/V2L DMAC is identical to one found on
the RZ/G2L SoC. No driver changes are required as generic compatible
string "renesas,rz-dmac" will be used as a fallback.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20220110134659.30424-9-prabhakar.mahadev-lad.rj@bp.renesas.com


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