team: Add vlan tx offload to hw_enc_features

We should also enable team's vlan tx offload in hw_enc_features,
pass the vlan packets to the slave devices with vlan tci, let the
slave handle vlan tunneling offload implementation.

Fixes: 3268e5cb ("team: Advertise tunneling offload features")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>