Fix for upstream mapper

subtree for empty quote doesn't work, use root "/".

Change-Id: I1b27ead855535488617a0fca950b187f90986b9b
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/src/EntityManager.cpp b/src/EntityManager.cpp
index bbd83c8..a0fa904 100644
--- a/src/EntityManager.cpp
+++ b/src/EntityManager.cpp
@@ -200,7 +200,7 @@
         },
         "xyz.openbmc_project.ObjectMapper",
         "/xyz/openbmc_project/object_mapper",
-        "xyz.openbmc_project.ObjectMapper", "GetSubTree", "", MAX_MAPPER_DEPTH,
+        "xyz.openbmc_project.ObjectMapper", "GetSubTree", "/", MAX_MAPPER_DEPTH,
         objects);
 }
 // probes dbus interface dictionary for a key with a value that matches a regex