nexthop: Fix data-races around nexthopcompatmode.
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 v5.15.56 by commit 0d17723afea3ae8c9f245c9bbd2ba5945b77e812, it was introduced in version v5.8 by commit 4f80116d3df3b23ee4b83ea8557629e1799bc230. For more details please see the references link.