staging: comedi: addi_apci_3xxx: tidy up the digital in and out subdevice init

staging: comedi: addi_apci_3xxx: tidy up the digital in and out subdevice init

For aesthetic reasons, add some whitespace to the initialization of the
digital input and output subdevices.

Fix the subdev_flags for both subdevices. The SDF_GROUND and SDF_COMMON
flags only apply to analog subdevices. Digital output subdevices do not
need the SDF_READABLE flag set.

Remove the initialization of s->io_bits. It only has meaning for
COMEDI_SUBD_DIO subdevices.

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>