iommu: Introduce iotlb_sync_map callback

Introduce iotlb_sync_map() callback that is invoked in the end of
iommu_map(). This new callback allows IOMMU drivers to avoid syncing
after mapping of each contiguous chunk and sync only when the whole
mapping is completed, optimizing performance of the mapping operation.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>