[BUGFIX] Correct upload field name for TCA internal_type file

Enforcing a file doesn't take the file upload field into
consideration. Correct the name of the check in JavaScript.

Resolves: #47372
Releases: master,6.2
Change-Id: I6958cc32afb72ac0998bb3c4ae99de14ba39aef8
Reviewed-on: http://review.typo3.org/37523


Reviewed-by: Rudy Gnodde <rgn@windinternet.nl>
Tested-by: Rudy Gnodde <rgn@windinternet.nl>
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>