dmaengine: pl330: Add IOMMU support to slave tranfers

Wire up dma_map_resource() for slave transfers, so that we can let the
PL330 use IOMMU-backed DMA mapping ops on systems with an appropriate
IOMMU and RAM above 4GB, to avoid CPU bounce buffering.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>