staging: comedi: ni_at_ao: rename the rest of the register map

For aesthetics, rename the remaining register map defines so they
follow the same format as the ones already renamed.

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>