i40e: suppress bogus error message

The i40e driver complains about unprivileged VFs trying to configure
promiscuous mode each time a VF reset occurs. This isn't the fault of
the poor VF driver - the PF driver itself is making the request.

To fix this, skip the privilege check if the request is to disable all
promiscuous activity. This gets rid of the bogus message, but doesn't
affect privilege checks, since we really only care if the unprivileged
VF is trying to enable promiscuous mode.

Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>