pppoe: uninitialized variable in pppoe_flush_dev()

This assignment got deleted along with the checks by mistake.  This
comes from:  8753d29f "pppoe: remove unnecessary checks in
pppoe_flush_dev"
Signed-off-by: NDan Carpenter <error27@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/pppoe.c

@@ -289,6 +289,7 @@ static void pppoe_flush_dev(struct net_device *dev)
 	struct pppoe_net *pn;
 	int i;
 
+	pn = pppoe_pernet(dev_net(dev));
 	write_lock_bh(&pn->hash_lock);
 	for (i = 0; i < PPPOE_HASH_SIZE; i++) {
 		struct pppox_sock *po = pn->hash_table[i];