vfio: allow secondary process to query IOMMU type

vfio: allow secondary process to query IOMMU type

It is only possible to know IOMMU type of a given VFIO container
by attempting to initialize it. Since secondary process never
attempts to set up VFIO container itself (because they're shared
between primary and secondary), it never knows which IOMMU type
the container is using, and never sets up the appropriate config
structures. This results in inability to perform DMA mappings in
secondary process.

Fix this by allowing secondary process to query IOMMU type of
primary's default container at device initialization.

Note that this fix is assuming we're only interested in default
container.

Bugzilla ID: 174
Fixes: 6bcb7c95fe14 ("vfio: share default container in multi-process")
Cc: stable@dpdk.org
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>