net: add netdev_lock() / netdev_unlock() helpers

Add helpers for locking the netdev instance, use it in drivers
and the shaper code. This will make grepping for the lock usage
much easier, as we extend the lock to cover more fields.

Reviewed-by: Joe Damato <jdamato@fastly.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Link: https://patch.msgid.link/20250115035319.559603-2-kuba@kernel.org


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