i40e: use priv flags to control flow director

i40e: use priv flags to control flow director

Orabug: 22342532

Some customers wish to be able to control our hardware specific
feature called flow director, at runtime.  This patch enables
ethtool priv flags to control this driver/hardware specific feature.

ethtool --set-priv-flags ethX flow-director-atr off

NOTE: the ethtool ntuple interface controls the flow-director
      sideband rules.

Change-ID: Iba156350b07fa2ce66f53ded51739f9a3781fe0e
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
(cherry picked from commit ef17178cf5abe304b2098a50f580e8c19e5084d2)
Signed-off-by: Brian Maly <brian.maly@oracle.com>