staging: comedi: cb_das16_cs: define the misc1 and misc2 register bits

Define the bits in these registers and use them to remove the "magic"
values in the driver.

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>