net: Add ndo_fcoe_get_wwn to net_device_ops

Add ndo_fcoe_get_wwn so Fiber Channel over Ethernet (FCoE) can make use of
the provided World Wide Port Name (WWPN) and World Wide Node Name (WWNN)
from the underlying network interface driver.

Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>