dt-bindings: dma: dw: Add max burst transaction length property

This array property is used to indicate the maximum burst transaction
length supported by each DMA channel.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/20200723005848.31907-3-Sergey.Semin@baikalelectronics.ru


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