vfio: use contiguous mapping for IOVA as VA mode

vfio: use contiguous mapping for IOVA as VA mode

When using IOVA as VA mode, there is no need to map segments
page by page. This normally isn't a problem, but it becomes one
when attempting to use DPDK in no-huge mode, where VFIO subsystem
simply runs out of space to store mappings.

Fix this for x86 by triggering different callbacks based on whether
IOVA as VA mode is enabled.

Fixes: 73a639085938 ("vfio: allow to map other memory regions")
Cc: stable@dpdk.org
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Tested-by: Andrius Sirvys <andrius.sirvys@intel.com>