staging: comedi: usbduxsigma: remove tidy_up() from (*auto_attach)

Comedi drivers do not need to cleanup allocations during the
(*auto_attach). If the (*auto_attach) fails the (*detach) will
automatically be called to handle the cleanup.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>