i40e: include i40e in kernel proper

This patch adds the changes for Kconfig, i40e.txt, MAINTAINERS, Kbuild
and new i40e/Makefile to build i40e with the kernel.

New driver build option is CONFIG_I40E

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
CC: PJ Waskiewicz <peter.p.waskiewicz.jr@intel.com>
CC: e1000-devel@lists.sourceforge.net
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/Documentation/networking/00-INDEX b/Documentation/networking/00-INDEX
index 18b64b2..f11580f 100644
--- a/Documentation/networking/00-INDEX
+++ b/Documentation/networking/00-INDEX
@@ -86,6 +86,8 @@
 	- info on Generic Netlink
 gianfar.txt
 	- Gianfar Ethernet Driver.
+i40e.txt
+	- README for the Intel Ethernet Controller XL710 Driver (i40e).
 ieee802154.txt
 	- Linux IEEE 802.15.4 implementation, API and drivers
 igb.txt