mctp: Fix incorrect netdev unref for extended addr

In the extended addressing local route output codepath
dev_get_by_index_rcu() doesn't take a dev_hold() so we shouldn't
dev_put().
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mctp/route.c

@@ -838,7 +838,6 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
 	struct mctp_skb_cb *cb = mctp_cb(skb);
 	struct mctp_route tmp_rt = {0};
 	struct mctp_sk_key *key;
-	struct net_device *dev;
 	struct mctp_hdr *hdr;
 	unsigned long flags;
 	unsigned int mtu;
@@ -851,12 +850,12 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
 
 	if (rt) {
 		ext_rt = false;
-		dev = NULL;
-
 		if (WARN_ON(!rt->dev))
 			goto out_release;
 
 	} else if (cb->ifindex) {
+		struct net_device *dev;
+
 		ext_rt = true;
 		rt = &tmp_rt;
 
@@ -866,7 +865,6 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
 			rcu_read_unlock();
 			return rc;
 		}
-
 		rt->dev = __mctp_dev_get(dev);
 		rcu_read_unlock();
 
@@ -947,11 +945,9 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
 	if (!ext_rt)
 		mctp_route_release(rt);
 
-	dev_put(dev);
 	mctp_dev_put(tmp_rt.dev);
 
 	return rc;
-
 }
 
 /* route management */