Make sure to echo xprofile visibility label 'for' attribute

The echo was mistakenly removed in r8210, with the result that in BP 2.0 it
was not possible to click on the <label> elements to select visibility radio
buttons.

Fixes #5693

Props SGr33n

git-svn-id: https://buddypress.svn.wordpress.org/trunk@8489 cdf35c40-ae34-48e0-9cc9-0c9da1808c22