Yes, you can submit all diagrams created by Matlab without any problems. They are your personal property.
You could mention, that you have used Matlab by "MATLAB 2017a, The MathWorks, Inc." and for the readers it might be useful to explain which toolboxes have been used. But these information are NOT mandatory.
[EDITED: NOT mandatory. I wanted to say, that it is "not obligatory", but the opposite is "optional".]
