iavf: Add support for VIRTCHNL_VF_OFFLOAD_VLAN_V2 negotiation

In order to support the new VIRTCHNL_VF_OFFLOAD_VLAN_V2 capability the
VF driver needs to rework it's initialization state machine and reset
flow. This has to be done because successful negotiation of
VIRTCHNL_VF_OFFLOAD_VLAN_V2 requires the VF driver to perform a second
capability request via VIRTCHNL_OP_GET_OFFLOAD_VLAN_V2_CAPS before
configuring the adapter and its netdev.

Add the VIRTCHNL_VF_OFFLOAD_VLAN_V2 bit when sending the
VIRTHCNL_OP_GET_VF_RESOURECES message. The underlying PF will either
support VIRTCHNL_VF_OFFLOAD_VLAN or VIRTCHNL_VF_OFFLOAD_VLAN_V2 or
neither. Both of these offloads should never be supported together.

Based on this, add 2 new states to the initialization state machine:

__IAVF_INIT_GET_OFFLOAD_VLAN_V2_CAPS
__IAVF_INIT_CONFIG_ADAPTER

The __IAVF_INIT_GET_OFFLOAD_VLAN_V2_CAPS state is used to request/store
the new VLAN capabilities if and only if VIRTCHNL_VLAN_OFFLOAD_VLAN_V2
was successfully negotiated in the __IAVF_INIT_GET_RESOURCES state.

The __IAVF_INIT_CONFIG_ADAPTER state is used to configure the
adapter/netdev after the resource requests have finished. The VF will
move into this state regardless of whether it successfully negotiated
VIRTCHNL_VF_OFFLOAD_VLAN or VIRTCHNL_VF_OFFLOAD_VLAN_V2.

Also, add a the new flag IAVF_FLAG_AQ_GET_OFFLOAD_VLAN_V2_CAPS and set
it during VF reset. If VIRTCHNL_VF_OFFLOAD_VLAN_V2 was successfully
negotiated then the VF will request its VLAN capabilities via
VIRTCHNL_OP_GET_OFFLOAD_VLAN_V2_CAPS during the reset. This is needed
because the PF may change/modify the VF's configuration during VF reset
(i.e. modifying the VF's port VLAN configuration).

This also, required the VF to call netdev_update_features() since its
VLAN features may change during VF reset. Make sure to call this under
rtnl_lock().

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>