Sensor reading support for Power Supply Redundancy

Added Power Supply Redundancy Sensor and prevented
setting the value.

Change-Id: If05ecb74c1e05ac59da1ae4dbb265ba65ce7744b
Signed-off-by: Dhruvaraj Subhashchandran <dhruvaraj@in.ibm.com>
diff --git a/obmc/sensors.py b/obmc/sensors.py
index dc74733..d3faef9 100644
--- a/obmc/sensors.py
+++ b/obmc/sensors.py
@@ -295,3 +295,14 @@
     def SystemStateHandler(self, state):
         if (state == "HOST_POWERED_OFF"):
             self.setValue("Off")
+
+class PowerSupplyRedundancySensor(VirtualSensor):
+    def __init__(self, bus, name):
+        VirtualSensor.__init__(self, bus, name)
+        super(PsRedundancySensor,self).setValue("Disabled")
+
+    ## override setValue method
+    @dbus.service.method(
+        SensorValue.IFACE_NAME, in_signature='v', out_signature='')
+    def setValue(self, value):
+        print "Setting Power Supply Redundancy is not allowed"