netfilter: ipset: fix list type element drift bug

netfilter: ipset: fix list type element drift bug

If list_set_uadd() calls list_set_replace() to swap an expired entry,
the element count remains the same, therefore the increment must be elided.

Fixes: 702b71e7c666 ("netfilter: ipset: Add element count to all set types header")
Link: https://sashiko.dev/#/patchset/20260806101947.2802-1-fw%40strlen.de
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>