[BUGFIX] RTE references non-existent xml files

References should be to xlf files.

Releases: master, 6.2
Resolves: #62112
Change-Id: I670e0f7f8af422d710c85c76f87b25527ceb1c38
Reviewed-on: http://review.typo3.org/33214
Reviewed-by: Stanislas Rolland <typo3@sjbr.ca>
Tested-by: Stanislas Rolland <typo3@sjbr.ca>