ix(4), ixv(4): VLAN tag stripping fixes for Amazon EC2 Enhanced Networking

From Piotr:

ix(4), ixv(4): Add VLAN tag strip check when receiving packets
ixv(4): Fix support for VLAN_HWTAGGING and VLAN_HWFILTER flags

This change will prevent driver from passing VLAN tags when
interface configuration is not expecting them. VF driver will
check for VLAN_HWTAGGING and VLAN_HWFILTER flags and act adequately.

This patch resolves problem occuring on EC2 platforms.

Submitted by: Piotr Pietruszewski <piotr.pietruszewski@intel.com>
Reported by: cperciva@
Reviewed by: cperciva@, Intel Networking
Approved by: re
Sponsored by: Intel Corporation
Differential Revision: https://reviews.freebsd.org/D17061