staging: comedi: remove comedi_debug module parameter

Remove this module parameter and use the CONFIG_COMEDI_DEBUG option to
enable normal kernel debugging with -DDEBUG flag.

Remove the #undef DEBUG from all the comedi source files so they will
honour the -DDEBUG flag.

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