netfilter: bridge: don't leak skb in error paths

netfilter: bridge: don't leak skb in error paths

commit dd302b59bde0149c20df7278c0d36c765e66afbd upstream.

br_nf_dev_queue_xmit must free skb in its error path.
NF_DROP is misleading -- its an okfn, not a netfilter hook.

Fixes: 462fb2af9788a ("bridge : Sanitize skb before it enters the IP stack")
Fixes: efb6de9b4ba00 ("netfilter: bridge: forward IPv6 fragmented packets")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
[bwh: Backported to 3.2:
 - Adjust filename
 - Drop IPv6 changes]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>