trace/fgraph: Fix the warning caused by missing unregister notifier

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CVE-2025-39829: Undefined Security Weakness

In the Linux kernel, the following vulnerability has been resolved: trace/fgraph: Fix the warning caused by missing unregister notifier This warning was triggered during testing on v6.16: notifier callback ftracesuspendnotifiercall already registered WARNING: CPU: 2 PID: 86 at kernel/notifier.c:2...