xProfile: when saving community profile changes in wp-admin, we don't need to split `$_POST['field_ids']` into a comma-seperated string before using `wp_parse_id_list()` as it will take care of that for us.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7970 cdf35c40-ae34-48e0-9cc9-0c9da1808c22