i40evf: main driver core

This is the driver for the Intel(R) XL710 X710 Virtual Function.

This patch contains the main driver entry points, but does not include
transmit and receive or ethtool functionality, which are presented as
separate patches in this series.

Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>