regulators: Add monitorSensors support to System

Implemented the monitorSensors() method in the System class.  This method
reads the sensors for the voltage rails produced by the system.

Signed-off-by: Bob King <Bob_King@wistron.com>
Change-Id: Ied2248c362708aa77c1efd31abff0cf023211a7e
diff --git a/phosphor-regulators/src/system.cpp b/phosphor-regulators/src/system.cpp
index 29dad5e..d3b599a 100644
--- a/phosphor-regulators/src/system.cpp
+++ b/phosphor-regulators/src/system.cpp
@@ -52,4 +52,13 @@
     }
 }
 
+void System::monitorSensors()
+{
+    // Monitor sensors in each chassis
+    for (std::unique_ptr<Chassis>& oneChassis : chassis)
+    {
+        oneChassis->monitorSensors(*this);
+    }
+}
+
 } // namespace phosphor::power::regulators