nfp: support TX VLAN ctag insert in NFDK

nfp: support TX VLAN ctag insert in NFDK

Add support for TX VLAN ctag insert
which may be configured via ethtool.
e.g.
     # ethtool -K $DEV tx-vlan-offload on

The NIC supplies VLAN insert information as packet metadata.
The fields of this VLAN metadata including vlan_proto and vlan tag.

Configuration control bit NFP_NET_CFG_CTRL_TXVLAN_V2 is to
signal availability of ctag-insert features of the firmware.

NFDK is used to communicate via PCIE to NFP-3800 based NICs
while NFD3 is used for other NICs supported by the NFP driver.
This features is currently implemented only for NFD3 and
this patch adds support for it with NFDK.

Signed-off-by: Diana Wang <[email protected]>
Reviewed-by: Louis Peens <[email protected]>
Signed-off-by: Simon Horman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>