CVE-2025-37932 sch_htb: make htb_qlen_notify() idempotent

In the Linux kernel, the following vulnerability has been resolved: schhtb: make htbqlennotify idempotent htbqlennotify always deactivates the HTB class and in fact could trigger a warning if it is already deactivated. Therefore, it is not idempotent and not friendly to its callers, like...