iavf: Add support for VIRTCHNL_VF_OFFLOAD_VLAN_V2 offload enable/disable

The new VIRTCHNL_VF_OFFLOAD_VLAN_V2 capability added support that allows
the VF to support 802.1Q and 802.1ad VLAN insertion and stripping if
successfully negotiated via VIRTCHNL_OP_GET_OFFLOAD_VLAN_V2_CAPS.
Multiple changes were needed to support this new functionality.

1. Added new aq_required flags to support any kind of VLAN stripping and
   insertion offload requests via virtchnl.

2. Added the new method iavf_set_vlan_offload_features() that's
   used during VF initialization, VF reset, and iavf_set_features() to
   set the aq_required bits based on the current VLAN offload
   configuration of the VF's netdev.

3. Added virtchnl handling for VIRTCHNL_OP_ENABLE_STRIPPING_V2,
   VIRTCHNL_OP_DISABLE_STRIPPING_V2, VIRTCHNL_OP_ENABLE_INSERTION_V2,
   and VIRTCHNL_OP_ENABLE_INSERTION_V2.

Signed-off-by: Brett Creeley <brett.creeley@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>