iommu/amd: Remove map_sg_no_iommu()

This function was intended as a fall-back if the map_sg
function is called for a device not mapped by the IOMMU.
Since the AMD IOMMU driver uses per-device dma_ops this can
never happen. So this function isn't needed anymore.

Reviewed-by: Shuah Khan <shuahkhan@gmail.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>