Revert Fix vdev_probe() call wrt SCL_STATE_ALL

This reverts commit cc9c6bc, which has been causing intermittent
test failures on buildbot.  A correct fix for this locking issue
has been applied in a separate patch.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>

module/zfs/zio.c

@@ -3325,7 +3325,7 @@ zio_vdev_io_done(zio_t *zio)
 
 	ops->vdev_op_io_done(zio);
 
-	if (unexpected_error && zio->io_waiter != NULL)
+	if (unexpected_error)
 		VERIFY(vdev_probe(vd, zio) == NULL);
 
 	return (ZIO_PIPELINE_CONTINUE);