netfilter: nf_tables: do not store pktinfo in traceinfo structure

pass it as argument.  No change in object size.

stack usage decreases by 8 byte:
 nf_tables_core.c:254  nft_do_chain       320     static

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>