devlink: fix netns refcount leak in devlink_nl_cmd_reload()

In the Linux kernel, the following vulnerability has been resolved: devlink: fix netns refcount leak in devlink_nl_cmd_reload() While preparing my patch series adding netns refcount tracking, I spotted bugs in devlink_nl_cmd_reload() Some error paths forgot to release a refcount on a netns. To fix this, we can reduce the scope of get_net()/put_net() section around the call to devlink_reload().