obmc-libobmc-intf: Add Swift gpio definitions

Add gpio definitions for the Swift machine under a swift subdir.
Move the witherspoon gpio definitions under a witherspoon subdir.

Tested: Built swift and witherspoon and checked that the file
        rootfs/etc/default/obmc/gpio/gpio_defs.json was correct
        for each machine.

Change-Id: I4de5b4e001556cfc02f09959eb371f61f0e3298c
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
3 files changed