netfilter: bridge: refcount fix

commit f216f082
([NETFILTER]: bridge netfilter: deal with martians correctly)
added a refcount leak on in_dev.

Instead of using in_dev_get(), we can use __in_dev_get_rcu(),
as netfilter hooks are running under rcu_read_lock(), as pointed
by Patrick.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>

net/bridge/br_netfilter.c

@@ -359,7 +359,7 @@ static int br_nf_pre_routing_finish(struct sk_buff *skb)
 				},
 				.proto = 0,
 			};
-			struct in_device *in_dev = in_dev_get(dev);
+			struct in_device *in_dev = __in_dev_get_rcu(dev);
 
 			/* If err equals -EHOSTUNREACH the error is due to a
 			 * martian destination or due to the fact that