Hotfix add closure load_callback

[zonky2]

Hotfix add closure load_callback - #151

            'mcw_text' => array
                (
                'label'         => &$GLOBALS['TL_LANG'][$strTblName]['mcw_text'],
                'exclude'       => true,
                'inputType'     => 'text',
                'eval'          => array('style'=>'width:150px'),
                'load_callback' => function($varValue, $dc) 
                    {
                        return 2;
                    }
                ),