[BUGFIX] Link to ext:perm in clickmenu not working

The link refers directly to index.php instead of mod.php.
Use BackendUtility::getModuleUrl() for the link to fix the problem.

Change-Id: I7cdda9f592e331c95bbb3c5d301907bd77761ec5
Resolves: #62459
Related: #38099
Releases: master, 6.2, 6.1
Reviewed-on: http://review.typo3.org/33551
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>