netfilter: nf_tables: skip set commit for deleted/destroyed sets

netfilter: nf_tables: skip set commit for deleted/destroyed sets

NFT_MSG_DELSET deactivates all elements in the set, skip
set->ops->commit() to avoid the unnecessary clone (for the pipapo case)
as well as the sync GC cycle, which could deactivate again expired
elements in such set.

Fixes: 5f68718b34a5 ("netfilter: nf_tables: GC transaction API to avoid race with control plane")
Reported-by: Kevin Rich <kevinrich1337@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>