i40e: adds FCoE code to the i40e driver

This patch adds FCoE ( Fibre Channel Over Ethernet ) code for
Intel XL710 adapters. This patch is limited to only new FCoE
offloads code in newly added files by this patch and then
following patches in the series modifies rest of the existing
driver to enable FCoE with i40e driver.

Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Tested-by: Jack Morgan<jack.morgan@intel.com>
Signed-off-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>