usb-host: fix streams detection in usb_host_speed_compat

The companion descriptor is present on all usb3 devices, not only
those with streams support.  We need to check attributes to see
whenever the device uses streams or not.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 1473406890-30164-1-git-send-email-kraxel@redhat.com
