bridge: netfilter: Fix dropping packets that moving through bridge interface

Problem:
br_nf_pre_routing_finish() calls itself instead of
br_nf_pre_routing_finish_bridge(). Due to this bug reverse path filter drops
packets that go through bridge interface.

User impact:
Local docker containers with bridge network can not communicate with each
other.

Fixes: c5136b15 ("netfilter: bridge: add and use br_nf_hook_thresh")
Signed-off-by: Artur Molchanov <artur.molchanov@synesis.ru>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>