dt-bindings: dma: mv-xor-v2: Convert to dtschema

Convert txt bindings of Marvell XOR v2 engines to dtschema to allow
for validation.

Also add missing property `dma-coherent` as `drivers/dma/mv_xor_v2.c`
calls various dma-coherent memory functions.

Signed-off-by: Shresth Prasad <shresthprasad7@gmail.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20240723095518.9364-2-shresthprasad7@gmail.com


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