DataGroup Length Indicator bug fix (it's inserted in the same X-PAD fiel...

Hi
This is the updated version compliant with Paragraph 7.4.5.1.4 of ets 300 401
![csp_dab_mot_encoding](https://f.cloud.github.com/assets/7050465/2509682/3812c71a-b3f9-11e3-8538-516e3a0e8ca8.jpg)