i40e: start up in VEPA mode by default

The patch fixes a bug in the default configuration which
prevented a software bridge loaded on the PF interface from
working correctly because broadcast packets are incorrectly
looped back.

Fix the general case, by loading the driver in VEPA mode Until a
VF or VMDq VSI is added. This way loopback on the Main VSI is
turned off until needed and can resolve the issue of unnecessary
reflection for users that do not have VF or VMDq VSIs setup.

The driver must now coordinate the loopback setting for the Flow
Director (FDIR) VSI to make sure it is in sync with the current
VEB or VEPA mode setting.

The user can still switch bridge modes from the bridge commands and
choose to be in VEPA mode with VF VSIs. Because of hardware
requirements, the call to switch to VEB mode when no VF/VMDqs are
present will be rejected.

NOTE: This patch uses BIT_ULL as that is preferred going forward,
a followup patch in the lower priority queue to net-next will fix
up the remaining 1 << usages.

Change-ID: Ib121ddb18fe4b3c4f52e9deda6fcbeb9105683d1
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>