staging: comedi: adv_pci1724: define the sync output control/status reg

Define the bits for the synchronous output control/status register and
remove the enum.

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>