i40e: don't add broadcast filter for VFs

Now that all VSIs are configured to receive broadcasts as default, we
don't need to add a filter. This eliminates an annoying but harmless
error message each time VFs are created or reset.

Change-ID: I4cd6339684df45b0d2722133eeb84c14fa93ea19
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>