iavf: Add support VIRTCHNL_VF_OFFLOAD_VLAN_V2 during netdev config

Based on VIRTCHNL_VF_OFFLOAD_VLAN_V2, the VF can now support more VLAN
capabilities (i.e. 802.1AD offloads and filtering). In order to
communicate these capabilities to the netdev layer, the VF needs to
parse its VLAN capabilities based on whether it was able to negotiation
VIRTCHNL_VF_OFFLOAD_VLAN or VIRTCHNL_VF_OFFLOAD_VLAN_V2 or neither of
these.

In order to support this, add the following functionality:

iavf_get_netdev_vlan_hw_features() - This is used to determine the VLAN
features that the underlying hardware supports and that can be toggled
off/on based on the negotiated capabiltiies. For example, if
VIRTCHNL_VF_OFFLOAD_VLAN_V2 was negotiated, then any capability marked
with VIRTCHNL_VLAN_TOGGLE can be toggled on/off by the VF. If
VIRTCHNL_VF_OFFLOAD_VLAN was negotiated, then only VLAN insertion and/or
stripping can be toggled on/off.

iavf_get_netdev_vlan_features() - This is used to determine the VLAN
features that the underlying hardware supports and that should be
enabled by default. For example, if VIRTHCNL_VF_OFFLOAD_VLAN_V2 was
negotiated, then any supported capability that has its ethertype_init
filed set should be enabled by default. If VIRTCHNL_VF_OFFLOAD_VLAN was
negotiated, then filtering, stripping, and insertion should be enabled
by default.

Also, refactor iavf_fix_features() to take into account the new
capabilities. To do this, query all the supported features (enabled by
default and toggleable) and make sure the requested change is supported.
If VIRTCHNL_VF_OFFLOAD_VLAN_V2 is successfully negotiated, there is no
need to check VIRTCHNL_VLAN_TOGGLE here because the driver already told
the netdev layer which features can be toggled via netdev->hw_features
during iavf_process_config(), so only those features will be requested
to change.

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>