vdpa/mlx5: backport fix for vdpa
JIRA: https://issues.redhat.com/browse/RHEL-814
test by:QE
upstream: https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git
build: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=54665563
Signed-off-by: Cindy Lu lulu@redhat.com
Edited by Cindy Lu