staging: comedi: pcl816: remove use of DPRINTK

Remove the DPRINTK messages that are just function trace noise.

Use dev_dbg() instead of the DPRINTK macro to output the comedi
debugging information.

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>