e1000: add missed define for VFTA

VLAN filtering using the VFTA (VLAN Filter Table Array) and
should be initialized prior to setting rx mode.

Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Signed-off-by: Guinan Sun <guinanx.sun@intel.com>
Reviewed-by: Wei Zhao <wei.zhao1@intel.com>

Approved by: imp
Obtained from: DPDK (fc9933953c90e99970aa867c38f9c6e6c5d0488d)
MFC after: 1 week