sctp: Avoid enqueuing addr events redundantly

Avoid modifying or enqueuing new events if it's possible to tell that no
one will consume them.

Since enqueueing requires searching the current queue for opposite
events for the same address, adding addresses en-masse turns this
inetaddr_event into a bottle-neck, as it will get slower and slower
with each address added.

Signed-off-by: Gilad Naaman <gnaaman@drivenets.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20241104083545.114-1-gnaaman@drivenets.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>