[BUGFIX] ExtendedFileUtility.php: func_delete

This fixes an issue within method func_delete trying to catch a file
access exception instead of expected folder access exception during
delete of an folder.

Change-Id: Iaf76100cd668ef4b1a36a5d9052a6f185ffa6b7b
Resolves: #56511
Releases: 6.2
Reviewed-on: https://review.typo3.org/28019
Reviewed-by: Frans Saris
Reviewed-by: Christian Weiske
Tested-by: Christian Weiske
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters