net: Hold rtnl_net_lock() in (un)?register_netdevice_notifier_dev_net().

(un)?register_netdevice_notifier_dev_net() hold RTNL before triggering
the notifier for all netdev in the netns.

Let's convert the RTNL to rtnl_net_lock().

Note that move_netdevice_notifiers_dev_net() is assumed to be (but not
yet) protected by per-netns RTNL of both src and dst netns; we need to
convert wireless and hyperv drivers that call dev_change_net_namespace().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250106070751.63146-4-kuniyu@amazon.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>