bonding: fix a buffer overflow in bonding_show_queue_id.

The test for buffer overflow ensures we have room for 6 more bytes.
sprintf, called with %s:%d, slave->dev->name, slave->queue_id may yield
far more than 6 bytes.

The correct test is res > (PAGE_SIZE - IFNAMSIZ - 6) .

Signed-off-by: Nicolas de Pesloüan <nicolas.2p.debian@free.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>