Adapt 2796f7cab10785ef40efbba97ef67ab319c96e9c to igc(4)
* Don't reset the entire adapter for vlan changes, fix up the problems
* Add some functions for vlan filter (vfta) manipulation
* Don't muck with the vfta if we aren't doing HW vlan filtering* Remove the VFTA, this hardware doesn't seem to implement it