vfio/mbochs: Use mdev_get_type_group_id()

The mbochs_types array is parallel to the supported_type_groups array, so
the type_group_id indexes both. Instead of doing string searching just
directly index with type_group_id in all places.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <14-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>