i40e: Prevent deleting MAC address from VF when set by PF

To prevent VF from deleting MAC address that was assigned by the
PF we need to check for that scenario when we try to delete a MAC
address from a VF.

Signed-off-by: Patryk Małek <patryk.malek@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>