Update vdev_ops_t from illumos
Align vdev_ops_t from illumos for better compatibility.
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Igor Kozhukhov <igor@dilos.org>
Closes #8925