[BUGFIX] Filelist: Removed call to deprecated method render()

Call of FlashMessage->render() when storage is not browsable is replaced
with appropriate code.

Resolves: #72507
Releases: master, 7.6
Change-Id: I3ecc251e1c5c4626773ee1b9c96c34308ab52442
Reviewed-on: https://review.typo3.org/45553


Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Sebastian Fischer <typo3@evoweb.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>