[BUGFIX] accessibilityWrap ignores simple value

Radio buttons with accessibilityWrap must use simple value
if no complex configuration is supplied. An extra dot prevented
this.

Change-Id: Ie9fa38f075eb5c4b9bfa4679f08bb325b9e177ac
Fixes: #38791
Releases: 4.5, 4.6, 4.7, 6.0
Reviewed-on: http://review.typo3.org/12728
Reviewed-by: Jigal van Hemert
Tested-by: Jigal van Hemert