Remove One chassis option

The One chassis option has been gone for a long time, but this ifdef
looks like it got missed.  Remove it.

Tested: code compiles.

Change-Id: I013e824806e72bc608ae4383ce4ba707641aeec6
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/redfish-core/lib/redfish_util.hpp b/redfish-core/lib/redfish_util.hpp
index 5d8c0e6..8fe2bbc 100644
--- a/redfish-core/lib/redfish_util.hpp
+++ b/redfish-core/lib/redfish_util.hpp
@@ -14,7 +14,6 @@
 // limitations under the License.
 */
 #pragma once
-#ifndef BMCWEB_ENABLE_REDFISH_ONE_CHASSIS
 
 #include "async_resp.hpp"
 #include "dbus_utility.hpp"
@@ -257,4 +256,3 @@
 }
 
 } // namespace redfish
-#endif