regulators: Add close method to Device class

Add a close method to the Device class.  This will be used to close all
devices in the system when monitoring is disabled.  Monitoring is
disabled when the system is being powered off.

Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
Change-Id: I0712ad698ebbcac5d7b17a822443b94dda230429
diff --git a/phosphor-regulators/src/device.hpp b/phosphor-regulators/src/device.hpp
index e9369fc..ab24e4b 100644
--- a/phosphor-regulators/src/device.hpp
+++ b/phosphor-regulators/src/device.hpp
@@ -86,6 +86,14 @@
     void addToIDMap(IDMap& idMap);
 
     /**
+     * Closes this device.
+     *
+     * Closes any interfaces that are open to this device.  Releases any other
+     * operating system resources associated with this device.
+     */
+    void close();
+
+    /**
      * Configure this device.
      *
      * Applies the configuration changes that are defined for this device, if