i40e: Expose 'trust' flag to userspace via ndo_get_vf_config.

This enables
	ip -d l
to indicate if trust is on or off for VFs.

Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>