net: pppoe - get rid of DECLARE_MAC_BUF

While was playing with PPP namespaces I occasionally brought
back DECLARE_MAC_BUF which is not needed (we have %pM here).
Fix it.
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/pppoe.c

@@ -1004,7 +1004,6 @@ static int pppoe_seq_show(struct seq_file *seq, void *v)
 {
 	struct pppox_sock *po;
 	char *dev_name;
-	DECLARE_MAC_BUF(mac);
 
 	if (v == SEQ_START_TOKEN) {
 		seq_puts(seq, "Id       Address              Device\n");