dt-bindings: dma: Add bindings for Intel LGM SoC

Add DT bindings YAML schema for DMA controller driver
of Lightning Mountain (LGM) SoC.

Signed-off-by: Amireddy Mallikarjuna reddy <mallikarjunax.reddy@linux.intel.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/f307e9012680a300a4dbaf4c7e0e83ca05fd9459.1606905330.git.mallikarjunax.reddy@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>