staging: comedi: serial2002: split up serial_2002_open()

Split out the code that sets up the comedi subdevices that are
attached to the serial port.

There are actually two steps:

1) Read the configuration of the attached subdevices.
2) Use the configuration data to setup the comedi subdevices.

Step 1 is split out as serial2002_setup_subdevs().
Step 2 is split out as serial2002_setup_subdevice().

Cleanup the split out code to remove all the extra '{ }' and indents.
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>