net: no longer acquire RTNL in threaded_show()

dev->threaded can be read locklessly, if we add
corresponding READ_ONCE()/WRITE_ONCE() annotations.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240502173926.2010646-1-edumazet@google.com


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