Consitently use dbus::utility types

This saves about 4k on the binary size

Tested: Redfish service validator passes.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I9546227a19c691b1aecb80e80307889548c0293f
diff --git a/redfish-core/lib/redfish_util.hpp b/redfish-core/lib/redfish_util.hpp
index a42d00d..7af4ab8 100644
--- a/redfish-core/lib/redfish_util.hpp
+++ b/redfish-core/lib/redfish_util.hpp
@@ -56,7 +56,7 @@
     crow::connections::systemBus->async_method_call(
         [callback,
          asyncResp](const boost::system::error_code ec,
-                    const crow::openbmc_mapper::GetSubTreeType& subtree) {
+                    const dbus::utility::MapperGetSubTreeResponse& subtree) {
             if (ec)
             {
                 BMCWEB_LOG_ERROR << ec;