vfio/common: Introduce vfio_container_add|del_section_window()

vfio/common: Introduce vfio_container_add|del_section_window()

Introduce helper functions that isolate the code used for
VFIO_SPAPR_TCE_v2_IOMMU.

Those helpers hide implementation details beneath the container object
and make the vfio_listener_region_add/del() implementations more
readable. No code change intended.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>