netfilter: nft_last: copy content when cloning expression

netfilter: nft_last: copy content when cloning expression

BugLink: https://bugs.launchpad.net/bugs/2016875
[ Upstream commit 860e874290fb3be08e966c9c8ffc510c5b0f2bd8 ]

If the ruleset contains last timestamps, restore them accordingly.
Otherwise, listing after restoration shows never used items.

Fixes: 33a24de37e81 ("netfilter: nft_last: move stateful fields out of expression data")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>