netfilter: bridge: query conntrack about skb dnat

ask conntrack instead of storing ipv4 address in nf_bridge_info->data.

Ths avoids the need to use ->data during NF_PRE_ROUTING.
Only two functions that need ->data remain.

These will be addressed in followup patches.

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

diff --cc include/linux/netfilter_bridge.h
Simple merge

diff --cc net/bridge/br_netfilter.c
Simple merge