staging: comedi: rtd520: remove the '#if 0' code in the attach

This driver has code #if 0'ed out that would allow cleaning up
the attach if there was an error. The comedi core currently
calls the detach function to do this if the attach fails.

Remove the #if 0'ed out code.

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>