dt-bindings: dma: rz-dmac: Document RZ/A1H SoC

Document the Renesas RZ/A1H DMAC block. This one does not have clocks,
resets and power domains. Update the bindings accordingly. Introduce a
generic name in the header to make future additions easier.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20241007110200.43166-7-wsa+renesas@sang-engineering.com


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