Setting a trusted i40e VF down results in the MAC address changing

Issue

• Setting a trusted i40e VF down results in the MAC address changing
• If an Intel 700 series SR-IOV VF has its MAC address set by the PF and is trusted, and the VM which owns the VF sets the VF down such as ip link set ethX down, then the VF MAC address changes to all zeroes 00:00:00:00:00:00. When the VF is set up again, it gets a random MAC address, not the same MAC address as previous. This does not happen with Intel's out-of-tree i40e driver.