dt-bindings: dmaengine: Introduce RZN1 DMA compatible

Just like for the NAND controller that is also on this SoC, let's
provide a SoC generic and a more specific couple of compatibles for the
DMA controller.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20220427095653.91804-4-miquel.raynal@bootlin.com


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