staging: comedi: addi_apci_2032: cleanup register map defines

Cleanup the defines a bit and add the missing information for the
bits in the registers.

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>