l2tp: prevent lockdep issue in l2tptunnelregister()
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 v5.15.91 by commit b2a730974373efa1050770c69ccd768eafdee19b, it was introduced in version v5.15.91 by commit 77e8ed776cdb1a24b2aab8fe7c6f1f154235e1ce. For more details please see the references link.