pseq: Add base and UCD90320 device monitor classes

Add a power sequencer device monitoring base class and a UCD90320
subclass. Update power controller class to construct and pass device
information to device class.  Update build file to support.

Signed-off-by: Jim Wright <jlwright@us.ibm.com>
Change-Id: Idf3ef53011b23f15841d93795f9f0995892b10b9
diff --git a/phosphor-power-sequencer/src/power_control.hpp b/phosphor-power-sequencer/src/power_control.hpp
index 1699dcc..62dfce2 100644
--- a/phosphor-power-sequencer/src/power_control.hpp
+++ b/phosphor-power-sequencer/src/power_control.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "power_interface.hpp"
+#include "power_sequencer_monitor.hpp"
 #include "utility.hpp"
 
 #include <gpiod.hpp>
@@ -69,6 +70,11 @@
     sdbusplus::bus::bus& bus;
 
     /**
+     * The power sequencer device to monitor.
+     */
+    std::unique_ptr<PowerSequencerMonitor> device;
+
+    /**
      * Indicates if a state transistion is taking place
      */
     bool inStateTransition{false};