Corrects typo made in 0212ecb.

Misplaced the bracket in the above commit, which was valid PHP but caused the following deprecated function notice in WordPress:

[09-Jun-2013 13:52:22 UTC] PHP Warning:  Missing argument 2 for wpdb::prepare(), called in /Users/paul/Sites/master/wp-content/plugins/wp-postratings/wp-postratings.php on line 630 and defined in /Users/paul/Sites/example.com/wp-includes/wp-db.php on line 990