nft: don't print rule counters unless verbose

Currently rule counters are always printed, but that's not the desired
behavior. We should only print them with the verbose flag. This broke
when the arguments of nft_rule_print_save() were changed to accept the
format instead of a counters flag.

Fixes: cdc78b1d6bd7 ("nft: convert rule into a command state structure")
Signed-off-by: Eric Garver <e@erig.me>
Signed-off-by: Florian Westphal <fw@strlen.de>