iommu/dma: Use the gfp parameter in __iommu_dma_alloc_noncontiguous()

This function does an allocation of a buffer to return to the caller and
then goes on to allocate some internal memory, eg the scatterlist and
IOPTEs.

Instead of hard wiring GFP_KERNEL and a wrong GFP_ATOMIC, continue to use
the passed in gfp flags for all of the allocations. Clear the zone and
policy bits that are only relevant for the buffer allocation before
re-using them for internal allocations.

Auditing says this is never called from an atomic context, so the
GFP_ATOMIC is the incorrect flag.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4-v3-76b587fe28df+6e3-iommu_map_gfp_jgg@nvidia.com


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