uas: Log a warning when we cannot use uas because the hcd lacks streams

So that an user who wants to use uas can see why he is not getting uas.

Also move the check down so that we don't warn if there are other reasons
why uas cannot work.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>