igb: Clean-up configuration of VF port VLANs

This patch is meant to clean-up the configuration of the VF port based VLAN
configuration.  The original logic was a bit muddled and had some
undesirable side effects such as VLANs being either completely stripped
from the port or VLANs being left when they shouldn't be.  The idea behind
this code is to avoid any events such as spurious spoof notifications when
we are removing one VLAN tag and replacing it with another.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>