This adds the helper for setting the nested domain to a device hence
enable nested domain usage on Intel VT-d.

Link: https://lore.kernel.org/r/20231026044216.64964-7-yi.l.liu@intel.comSigned-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>