iommu/fsl: Make iova dma_addr_t in the iommu_iova_to_phys API.

This is required in case of PAMU, as it can support a window size of up
to 64G (even on 32bit).

Signed-off-by: Varun Sethi <Varun.Sethi@freescale.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>