dt-bindings: dma: rz-dmac: Document clock-names and reset-names

Document clock-names and reset-names properties as we have multiple
clocks and resets.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230315064726.22739-1-biju.das.jz@bp.renesas.com


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