USB: legousbtower: stop interrupt-out URB unconditionally

Stop also the interrupt-out URB unconditionally in
tower_abort_transfers() which is called from release() (for connected
devices). Calling usb_kill_urb() for an idle URB is perfectly fine.

Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191105084152.16322-8-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>