staging: comedi: rti800: add some whitespace to the subdevice init

For aesthetic reasons, add some whitespace to the subdevice init
to make it more readable.

Remove the commented out init of subdevice 4, it's not allocated.
Add a comment about it.

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>