staging: comedi: amplc_dio200: shrink struct dio200_subdev_intr

Shave a few bytes off the size of `struct dio200_subdev_intr` by
rearranging members and changing two of them to bit-fields.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>