net/e1000: configure outer VLAN TPID field
net/e1000: configure outer VLAN TPID field

This patch enables configuring the outer TPID for double VLAN.
Note that all other TPID values, for single VLANs or inner VLAN in the
QinQ case, are read only.

Signed-off-by: Beilei Xing <7fb7e49de6d75fb4140bfcdada52e66859d93ebd@intel.com>
Acked-by: Helin Zhang <aba9dfdb1a6ec8bf1ff66b95272c029f8dfde1b1@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk