e1000: allow VLAN devices to use TSO and CSUM offload

This patch changes e1000 to set vlan_features so TSO and CSUM
offload can be used by VLAN devices, similar as with the other
Intel drivers.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>