[BUGFIX] Redundant compare: GeneralUtility::inList()

GeneralUtility::inList() does a comparison resulting in a boolean value.
Then based on this value it will return TRUE or FALSE.

It suffices to return the result of the comparison.

Change-Id: I12f9dd699a643a187f871940175e32ab2bcca7de
Resolves: #54017
Releases: 6.2
Reviewed-on: https://review.typo3.org/25713
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters