CVE-2026-23200 ipv6: Fix ECMP sibling count mismatch when clearing RTF_ADDRCONF

In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix ECMP sibling count mismatch when clearing RTFADDRCONF syzbot reported a kernel BUG in fib6addrt2node when adding an IPv6 route. 0 Commit f72514b3c569 "ipv6: clear RA flags when adding a static route" introduced logic to...