init: load factory properties

These properties are typically set at device provisioning time
or in the factory. They contain unit-specific data that isn't
touched by software updates or factory data reset. Only
read-only properties can be read by this mechanism.

Change-Id: Ifff9184f039072c3c0ce99f825c3075afb524514
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>