Add GPIO Presence

Add the GPIO Presence service file and needed Witherspoon
conf files for power supply GPIO presence detection.

Resolves openbmc/openbmc#1329

Change-Id: Ie8d5e3e6c2bda1c85fd10a4cffacfdd7ce9840ae
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
5 files changed