net: mana: Add support for vlan tagging

To support vlan, use MANA_LONG_PKT_FMT if vlan tag is present in TX
skb. Then extract the vlan tag from the skb struct, and save it to
tx_oob for the NIC to transmit. For vlan tags on the payload, they
are accepted by the NIC too.

For RX, extract the vlan tag from CQE and put it into skb.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>