kernel: devlink: hold region lock when flushing snapshots

In the Linux kernel, the following vulnerability has been resolved: devlink: hold region lock when flushing snapshots Netdevsim triggers a splat on reload, when it destroys regions with snapshots pending: WARNING: CPU: 1 PID: 787 at net/core/devlink.c:6291 devlinkregionsnapshotdel+0x12e/0x140 CPU...