[TASK] Introduce early returns in DataHandler::checkValue_flex_procInData_travDS()

Change-Id: If3fda1147813b2336b5fbeb7aee8cfa9f0fa5126
Resolves: #68209
Releases: master
Reviewed-on: http://review.typo3.org/41410


Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>