Revert "iommu/vt-d: Remove unused function"

Revert "iommu/vt-d: Remove unused function"

This reverts commit c61c255e114c52682546447ed44d3470b5708134.

The pasid_set_wpe() helper, which was removed by the reverted commit,
is still used by the nesting translation support in the iommufd tree.
To avoid a merge conflict, revert the commit.

Link: https://lore.kernel.org/linux-kernel/20231025153455.283c5b12@canb.auug.org.au/
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20231025131854.375388-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>