[BUGFIX] Use EXT: syntax for be_layout wizard icon

Change-Id: Iae3248f6548c07e4879423502fb3d5b29958fd88
Resolves: #70194
Releases: master
Reviewed-on: http://review.typo3.org/43634


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Michael Oehlhof <typo3@oehlhof.de>
Tested-by: Michael Oehlhof <typo3@oehlhof.de>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>