vfio: Prevent from pinned DMABUF importers to attach to VFIO DMABUF

vfio: Prevent from pinned DMABUF importers to attach to VFIO DMABUF

Some pinned importers, such as non-ODP RDMA ones, cannot invalidate their
mappings and therefore must be prevented from attaching to this exporter.

Fixes: 5d74781ebc86 ("vfio/pci: Add dma-buf export support for MMIO regions")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20260121-vfio-add-pin-v1-1-4e04916b17f1@nvidia.com
Signed-off-by: Alex Williamson <alex@shazbot.org>