staging: comedi: usbduxfast: absorb tidy_up() into the (*detach)

Now that the usb (*probe) is handled in the comedi_driver (*auto_attach)
the comedi_driver (*detach) will be called automatically if the
attach fails.

The tidy_up() calls in the (*auto_attach) are not needed. Remove them
and absorb the code in tidy_up() into the (*detach).

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>