Derive PGOODMonitor from DeviceMonitor

Adding this base class so that PGOODMonitor can
fulfill its true purpose, which is checking the
UCD90160 for errors on PGOOD failures.

Change-Id: Ie0637676ae5239c677d60f14d738ff9709d2b7b0
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
diff --git a/power-sequencer/pgood_monitor.cpp b/power-sequencer/pgood_monitor.cpp
index c4c88ca..2cafee6 100644
--- a/power-sequencer/pgood_monitor.cpp
+++ b/power-sequencer/pgood_monitor.cpp
@@ -84,6 +84,7 @@
 
     if (pgoodPending())
     {
+        device->onFailure();
         report<PowerOnFailure>();
     }