[FOLLOWUP][!!!][TASK] Drop TYPO3_CONF_VARS['SYS]['form_enctype']

Fix a typo

Change-Id: Ic36f85e7d6c29a8734cb83d1594e7a909c9646e1
Resolves: #68178
Releases: master
Reviewed-on: http://review.typo3.org/41325


Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>