CVE-2026-23168 flex_proportions: make fprop_new_period() hardirq safe

In the Linux kernel, the following vulnerability has been resolved: flexproportions: make fpropnewperiod hardirq safe Bernd has reported a lockdep splat from flexible proportions code that is essentially complaining about the following race: runtimersoftirq - we are in softirq context calltimerfn...