Get Device ID - JSON for Witherspoon

This is a reference for how to use get device ID with the witherspoon
platform. All other platforms that need get device ID should add
dev_id.json in their own machine specific bbappend files.

Change-Id: I0348748bfb9442d2de43b661cc291663f279efcb
Signed-off-by: David Cobbley <david.j.cobbley@linux.intel.com>