Update TbRelationalColumn.php

Line 160 in registerClientScript references a non existent property called submitData. This change adds the property so that it can be utilized. the functionality for using it already exists... on or around line 160...

```
     $data = !empty($this->submitData) && is_array($this->submitData) ? $this->submitData : 'js:{}';
      $data = CJavascript::encode($data);
```

and 

```
   var data = $.extend({$data}, {id:rowid});
```