staging: comedi: ni_pcidio: remove custom DPRINTK macro

The comedi core defines a DPRINTK macro in comedidev.h. Use that macro
instead of defining a private version in this driver.

Also, remove the DEBUG define since it was only used to enable the
DPRINTK macro.

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>