tmf: lttngControl: fix: way to retrieve probe and function information

Change-Id: Ie47ac49b58de165397be92b23161f90faf43772d
Signed-off-by: Jonathan Rajotte Julien <jonathan.rajotte-julien@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/32440
Tested-by: Hudson CI
Reviewed-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>