[BUGFIX] Avoid error message on unlimited upload_max_filesize

Resolves: #73214
Releases: master, 7.6
Change-Id: I9496964ffd9daeb2c330f022c876f6aceacced1c
Reviewed-on: https://review.typo3.org/47029


Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>