[BUGFIX] Fix wrong condition in method checkValueForText

This makes "eval" processing working again for text fields.

Resolves: #79545
Related: #79341
Releases: master
Change-Id: Icda2f32a41a95afa33c87be9ed60c5b5ed47f275
Reviewed-on: https://review.typo3.org/51465


Reviewed-by: Marcus Schwemer <ms@schwemer.de>
Tested-by: Marcus Schwemer <ms@schwemer.de>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>