udp: Update reuse->has_conns under reuseport_lock.
This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v5.15.76 by commit a8df9d0428c7b2e4f0c7ab8da3803f3fdddfce4d, it was introduced in version v5.4 by commit acdcecc61285faed359f1a3568c32089cc3a8329. For more details please see the references link.