Implement conditional netlink notifications for Qdiscs and classes,
which were missing in the initial patches that targeted tc filters and
actions. Notifications will only be built after passing a check for
'rtnl_notify_needed()'.

For both Qdiscs and classes 'get' operations now call a dedicated
notification function as it was not possible to distinguish between
'create' and 'get' before. This distinction is necessary because 'get'
always send a notification.
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://lore.kernel.org/r/20231229132642.1489088-2-pctammela@mojatatu.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>