Fix Association interface

Mapper changed to only allow the new interface, update
to it.

Tested: Mapper showed all associations

Change-Id: I8b252c70e9f27b083a438393c731fbeb3e2ca0e5
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/src/IpmbSensor.cpp b/src/IpmbSensor.cpp
index 946c060..cb7b705 100644
--- a/src/IpmbSensor.cpp
+++ b/src/IpmbSensor.cpp
@@ -80,8 +80,7 @@
         thresholdInterfaceCritical = objectServer.add_interface(
             dbusPath, "xyz.openbmc_project.Sensor.Threshold.Critical");
     }
-    association =
-        objectServer.add_interface(dbusPath, "org.openbmc.Associations");
+    association = objectServer.add_interface(dbusPath, association::interface);
     setupPowerMatch(conn);
 }