i40e: add wake-on-lan support

Wake on LAN is disabled by default and will remain that way for most
platforms, but there is an NVM setting that allows vendors to enable it
for a port if they think they've provided the right power environment
for the device.  This patch adds code to check the NVM setting and enable
Magic Packet use if WoL is enabled for the port.

Since only Magic Packet is supported, there's not a lot of HW configuration
needed.

Change-Id: I44e904a7b15695e34683009f487064cd86ea59b0
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>