staging: comedi: hwdrv_apci3120: cleanup printk messages

Remove the printk messages that are just driver development debug noise
and convert the rest to dev_err().

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>