staging: comedi: ni_at_ao: tidy up CFG1 register defines

Rename the defines for the CFG1 register so they have namespace
associated with 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>