[BUGFIX] Suggest wizard in flex forms

A broken variable access is fixed to hand over correct data
to the type=group suggest wizard.

Change-Id: I0c6dbf3d7da114f633e779eb594b6457a5e4fac6
Resolves: #79574
Related: #79440
Releases: master
Reviewed-on: https://review.typo3.org/51543


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>