COMP: Fix DiffusionTensorImagingTutorial

The XML file has been updated to account for the changes
added by previous updated related to introduction of
ctkSpinBox (r21902) and Editor layout re-organization.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22003 3bd1e089-480b-0410-8dfb-8563597acbee