netfilter: nft_quota: copy content when cloning expression

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

Restore the user-defined quota and flags too.

Fixes: ed0a0c60 ("netfilter: nft_quota: move stateful fields out of expression data")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>