bridge: Add const to dummy br_netpoll_send_skb

The version of br_netpoll_send_skb used when netpoll is off is
missing a const thus causing a warning.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/bridge/br_private.h

@@ -305,7 +305,7 @@ static inline struct netpoll_info *br_netpoll_info(struct net_bridge *br)
 	return NULL;
 }
 
-static inline void br_netpoll_send_skb(struct net_bridge_port *p,
+static inline void br_netpoll_send_skb(const struct net_bridge_port *p,
 				       struct sk_buff *skb)
 {
 }