iommufd: Add data structure for Intel VT-d stage-1 domain allocation

This adds IOMMU_HWPT_DATA_VTD_S1 for stage-1 hw_pagetable of Intel
VT-d and the corressponding data structure for userspace specified parameter
for the domain allocation.

Link: https://lore.kernel.org/r/20231026044216.64964-2-yi.l.liu@intel.com


Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>