Qt: fix small error

This was not correctly saving the last opened folder with some encoding
(cherry picked from commit 0fe06bc3f1cae8823f3a7baa012b1ff4e126a286)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/gui/qt4/dialogs_provider.cpp

@@ -506,7 +506,7 @@ static void openDirectory( intf_thread_t *p_intf, bool pl, bool go )
     if( dir.isEmpty() )
         return;
 
-    p_intf->p_sys->filepath = qtu( dir );
+    p_intf->p_sys->filepath = dir;
 
     const char *scheme = "directory";
     if( dir.endsWith( "/VIDEO_TS", Qt::CaseInsensitive ) )