[BUGFIX] Remove php warning for RTE classes without name

Check if name within the configuration is set
so that no PHP warning: illigal offset will be thrown

Resolves: #68068
Releases: master,6.2
Change-Id: I781fa237aa696e6e9b03714f8e1aca4124589d5f
Reviewed-on: http://review.typo3.org/42361


Reviewed-by: Daniel Maier <dani-maier@gmx.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Daniel Maier <dani-maier@gmx.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>