Add watches for throttling reported by the OCC

Add Error objects to watch the sysfs entries provided by the OCC hwmon
driver that report various types of throttling. Also needed to add a
boolean input to the Error callback interface.

Resolves openbmc/openbmc#1821

Change-Id: I4425770a92ace0f73024b3dc4c577ce46957a62a
Signed-off-by: Eddie James <eajames@us.ibm.com>
8 files changed