vxlan: call peernet2id() in fdb notification

netns id should be already allocated each time we change
netns, that is, in dev_change_net_namespace() (more precisely
in rtnl_fill_ifinfo()). It is safe to just call peernet2id() here.

Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 7a77dca..f3fa435 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -227,7 +227,6 @@
 		rtnl_net_notifyid(net, RTM_NEWNSID, id);
 	return id;
 }
-EXPORT_SYMBOL(peernet2id_alloc);
 
 /* This function returns, if assigned, the id of a peer netns. */
 int peernet2id(struct net *net, struct net *peer)
@@ -240,6 +239,7 @@
 	spin_unlock_irqrestore(&net->nsid_lock, flags);
 	return id;
 }
+EXPORT_SYMBOL(peernet2id);
 
 /* This function returns true is the peer netns has an id assigned into the
  * current netns.