i40e: VLAN field for flow director

Allow user to specify VLAN field and add it to flow director. Show VLAN
field in "ethtool -n ethx" command.
Handle VLAN type and tag field provided by ethtool command. Refactored
filter addition, by replacing static arrays with runtime dummy packet
creation, which allows specifying VLAN field.
Previously, VLAN field was omitted.

Signed-off-by: Przemyslaw Patynowski <przemyslawx.patynowski@intel.com>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>