iommu: Add a gfp parameter to iommu_map_sg()

Follow the pattern for iommu_map() and remove iommu_map_sg_atomic().

This allows __iommu_dma_alloc_noncontiguous() to use a GFP_KERNEL
allocation here, based on the provided gfp flags.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/3-v3-76b587fe28df+6e3-iommu_map_gfp_jgg@nvidia.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>