dmaengine: fsl-edma: dma map slave device address

This mapping needs to be created in order for slave dma transfers
to work on systems with SMMU. The implementation mostly mimics the
one in pl330 dma driver, authored by Robin Murphy.

Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Angelo Dureghello <angelo@sysam.it>
Signed-off-by: Vinod Koul <vkoul@kernel.org>