vdpa/mlx5: should not activate virtq object when suspended

Otherwise the virtqueue object to instate could point to invalid address
that was unmapped from the MTT:

  mlx5_core 0000:41:04.2: mlx5_cmd_out_err:782:(pid 8321):
  CREATE_GENERAL_OBJECT(0xa00) op_mod(0xd) failed, status
  bad parameter(0x3), syndrome (0x5fa1c), err(-22)

Fixes: cae15c2e ("vdpa/mlx5: Implement susupend virtqueue callback")
Cc: Eli Cohen <elic@nvidia.com>
Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>

Message-Id: <1676424640-11673-1-git-send-email-si-wei.liu@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>