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/include/Utils.hpp b/include/Utils.hpp
index abe5e7a..37b5a85 100644
--- a/include/Utils.hpp
+++ b/include/Utils.hpp
@@ -98,6 +98,12 @@
 const static constexpr char* property = "OperatingSystemState";
 } // namespace post
 
+namespace association
+{
+const static constexpr char* interface =
+    "xyz.openbmc_project.Association.Definitions";
+} // namespace association
+
 template <typename T>
 inline T loadVariant(
     const boost::container::flat_map<std::string, BasicVariantType>& data,