staging: comedi: 8255: refactor subdev_8255_init

Refactor the initialization of the 8255 so that the private data
allocation is done before the subdevice is setup. This makes sure
that the setup is complete.

Also, add a bit of whitespace to improve the readability.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Frank Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>