Fix EZP-21873 - Unable to use ez_render_field with ezgmaplocation_field

If you try to use
```
{{ ez_render_field( content, 'location' ) }}
```
on a gmaplocation_filed you'll get the following twig exception
```
 Key "width" for array with keys "" does not exist in EzPublishCoreBundle::content_fields.html.twig at line 306
500 Internal Server Error - Twig_Error_Runtime 
```
After investigating a bit more I found out that the problem is that the array parameters is empty