ixgbevf: fix VF untagging when 802.1 prio is set

We have had an issue when using ixgbe+ixgbevf and 802.1 VLAN tagging.

When attaching a VLAN to a VF, frames with a 802.1q priority appeared
untagged on the VF hence not reaching the VLAN, where frames with
priority 0 where tagged as expected and seen by the VLAN device.

This seems due to the way ixgbevf is looking up the full tag
(prio+cfi+vlan) against the adapter active_vlans, as a condition to mark
the skb tagged.

Signed-off-by: Pascal Bouchareine <pascal@gandi.net>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>