Remove unnecessary copy constructing ObjectManager

Change-Id: I62cca216546f82fa93cbdd22f40b00ca8c189859
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/mainloop.cpp b/mainloop.cpp
index 0077d33..b639539 100644
--- a/mainloop.cpp
+++ b/mainloop.cpp
@@ -146,7 +146,7 @@
     const char* prefix,
     const char* root)
     : _bus(std::move(bus)),
-      _manager(sdbusplus::server::manager::manager(_bus, root)),
+      _manager(_bus, root),
       _shutdown(false),
       _hwmonRoot(),
       _instance(),