staging: comedi: dt3000: remove dev_dbg() noise

Remove most of the dev_dbg() output from this driver. Most of it
is just noise.

For now I have left the dev_dbg() in the dt3k_send_cmd() function.
I still have not quite figured out how the low-level i/o works in
this driver...

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>