be2net: Enable NETIF_F_TSO6 for VLAN traffic for BE

NETIF_F_TSO6 for VLAN packets was not enabled for BE adapters.
Enabling it.

Signed-off-by: Padmanabh Ratnakar <padmanabh.ratnakar@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>