dmaengine: ti: k3-udma-glue: Add function to get device pointer for DMA API

Glue layer users should use the device of the DMA for DMA mapping and
allocations as it is the DMA which accesses to descriptors and buffers,
not the clients

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Link: https://lore.kernel.org/r/20201208090440.31792-5-peter.ujfalusi@ti.com


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