dt-bindings: ingenic: Add support for the JZ4755 dmaengine

Update documentation prior to adding driver changes.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Siarhei Volkau <lis8215@gmail.com>
Link: https://lore.kernel.org/r/20221019063934.3278444-2-lis8215@gmail.com


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