These complement the group interfaces used by VFIO and are for use by
iommufd. The main difference is that multiple devices in the same group
can all share the ownership by passing the same ownership pointer.

Move the common code into shared functions.

Link: https://lore.kernel.org/r/2-v6-a196d26f289e+11787-iommufd_jgg@nvidia.comTested-by: NNicolin Chen <nicolinc@nvidia.com>
Tested-by: NYi Liu <yi.l.liu@intel.com>
Tested-by: NLixiao Yang <lixiao.yang@intel.com>
Tested-by: NMatthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: NKevin Tian <kevin.tian@intel.com>
Reviewed-by: NEric Auger <eric.auger@redhat.com>
Signed-off-by: NLu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: NJason Gunthorpe <jgg@nvidia.com>