staging: comedi: das6402: remove DEBUG noise

The private data does not contain 'das6402_irqcount' or 'das6402_wordsread'
members so the printk noise produces build errors when DEBUG is defined.
The other printk is just added noise.

Remove the printk's to fix the build errors and remove the noise.

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>