[BUGFIX] #5094 Update script needs to update the number of images

Change-Id: If5ccceef46d59de8f0ebfca84d19adbe7587d998
Reviewed-on: http://review.typo3.org/34890
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>