Due to a hardware bug, reading memory (from the Accelerator Coherency Port)
with a burst size equal to the maximum burst size allowed by the DMA
hardware's buffer size will cause a hardware hang on the ARTPEC-6 SoC,
where the only solution is a manual power cycle.
On ARTPEC-6, this hardware bug does not trigger when writing memory (to the
Accelerator Coherency Port) with a burst size equal to the maximum burst
size allowed by the DMA hardware's buffer size.

To avoid this hardware hang, introduce a new optional max-burst property
for memory reads. For completeness, also introduce a max-burst property for
memory writes.

Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>