CVE-2026-74660 netfilter: ebt_nflog: pin the NFLOG backend

In the Linux kernel, the following vulnerability has been resolved: netfilter: ebtnflog: pin the NFLOG backend nflogunregister runs after the per-net teardown so its final RCU grace period also drains readers that obtained the logger from a per-net binding. However, ebtnflog passes an explicit UL...