Fix initial switch to folder in fileopen dlg

the argument passed is an URL, so using setDirectory wouldn't do
the trick, setDirectoryUrl would

Change-Id: I312f6e2a06b46777dc126f95f63ec0dbcb1f5799

vcl/unx/kde5/KDE5FilePicker2.cxx

@@ -213,7 +213,8 @@ void SAL_CALL KDE5FilePicker::setDisplayDirectory(const OUString& dir)
         return Q_EMIT setDisplayDirectorySignal(dir);
     }
 
-    _dialog->setDirectory(toQString(dir));
+    QString qDir(toQString(dir));
+    _dialog->setDirectoryUrl(QUrl(qDir));
 }
 
 OUString SAL_CALL KDE5FilePicker::getDisplayDirectory()