tmf.ui/timing: Update XY viewers even if there is no data

tmf.ui/timing: Update XY viewers even if there is no data

The range of the window still changed and the view should follow that
range, even though there is no data to display

Change-Id: Iaa6d180de39f6ee5b109ce5826999c096f170469
Signed-off-by: Genevieve Bastien <gbastien+lttng@versatic.net>
Reviewed-on: https://git.eclipse.org/r/83355
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Tested-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Reviewed-by: Hudson CI