USB: legousbtower: drop noisy disconnect messages

User space already sees -ENODEV in case it tries to do I/O post
disconnect, no need to spam the logs with printk messages that don't
even include any device-id information.

Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191105084152.16322-6-johan@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>