netns: bridge: allow unprivileged users add/delete mdb entry

since the mdb table is belong to bridge device,and the
bridge device can only be seen in one netns.
So it's safe to allow unprivileged user which is the
creator of userns and netns to modify the mdb table.
Signed-off-by: NGao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/bridge/br_mdb.c

@@ -272,9 +272,6 @@ static int br_mdb_parse(struct sk_buff *skb, struct nlmsghdr *nlh,
 	struct net_device *dev;
 	int err;
 
-	if (!capable(CAP_NET_ADMIN))
-		return -EPERM;
-
 	err = nlmsg_parse(nlh, sizeof(*bpm), tb, MDBA_SET_ENTRY, NULL);
 	if (err < 0)
 		return err;