[BUGFIX] Right tablename in front of the labels

The tablename of a e.g. content object should be tt_content
and not tx_exteky_domain_model_...

So the key in the XML is tt_content.FIELDNAME

Change-Id: I72cb8334dad5caa77916ebbb981703af3854a60c
Reviewed-on: http://review.typo3.org/32520
Reviewed-by: Tim Lochmüller <tim@fruit-lab.de>
Tested-by: Tim Lochmüller <tim@fruit-lab.de>