[BUGFIX] Warning in list module

The function addElement needs to have an array as third argument.

Change-Id: Iefb86fc6399a6aaee58f66c712ac81743c1bd2ac
Fixes: #39678
Releases: 4.5, 4.6, 4.7, 6.0
Reviewed-on: https://review.typo3.org/13875
Reviewed-by: Stefan Neufeind
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer