Fix top rated products shortcode

Fix this warning:

>**Warning:** call_user_func_array() expects parameter 1 to be a valid callback, first array member is not a valid class name or object in **......../wp-includes/plugin.php** on line **256**  
**WordPress database error**: [You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FROM wp_posts WHERE 1=1' at line 1]
SELECT FROM wp_posts WHERE 1=1

And some coding standards.