vdpa/mlx5: Take cvq iotlb lock during refresh

vdpa/mlx5: Take cvq iotlb lock during refresh

The reslock is taken while refresh is called but iommu_lock is more
specific to this resource. So take the iommu_lock during cvq iotlb
refresh.

Based on Eugenio's patch [0].

[0] https://lore.kernel.org/lkml/20230112142218.725622-4-eperezma@redhat.com/

Acked-by: Jason Wang <jasowang@redhat.com>
Suggested-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Message-Id: <20231018171456.1624030-9-dtatulea@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Si-Wei Liu <si-wei.liu@oracle.com>
Tested-by: Si-Wei Liu <si-wei.liu@oracle.com>
Tested-by: Lei Yang <leiyang@redhat.com>