USB: fix memleak in ark3116 serial driver

in an error case memory already allocated must be freed again.
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/ark3116.c

@@ -151,8 +151,10 @@ static int ark3116_attach(struct usb_serial *serial)
 	return 0;
 
 cleanup:
-	for (--i; i >= 0; --i)
+	for (--i; i >= 0; --i) {
+		kfree(usb_get_serial_port_data(serial->port[i]));
 		usb_set_serial_port_data(serial->port[i], NULL);
+	}
 	return -ENOMEM;
 }