Fix syntax error in ganalytics.php

Fix the following syntax error:

    PHP Parse error:  syntax error, unexpected ';', expecting ')' in /var/www/prestashop/modules/ganalytics/ganalytics.php on line 628

This bug (introduced in 6f1b2ca66df13a15d2e75d85b3c6327826fc44d0) actually breaks any Prestashop installation with an up to date Google Analytics module!