Fix shutdown ordering in DeviceControllerSystemState::Shutdown (#22048)

DeviceControllerSystemState shuts down PlatformMgr before higher
level objects that use timers such as ExchangeMgr.

This leads to calls into the system layer after it has been shut down.

Fix the ordering so that PlatformMgr is shut down last.

Co-authored-by: Andrei Litvin <[email protected]>

src/controller/CHIPDeviceControllerFactory.cpp

@@ -419,19 +419,6 @@ void DeviceControllerSystemState::Shutdown()
         mTransportMgr = nullptr;
     }
 
-#if CONFIG_DEVICE_LAYER
-    //
-    // We can safely call PlatformMgr().Shutdown(), which like DeviceController::Shutdown(),
-    // expects to be called with external thread synchronization and will not try to acquire the
-    // stack lock.
-    //
-    // Actually stopping the event queue is a separable call that applications will have to sequence.
-    // Consumers are expected to call PlaformMgr().StopEventLoopTask() before calling
-    // DeviceController::Shutdown() in the CONFIG_DEVICE_LAYER configuration
-    //
-    DeviceLayer::PlatformMgr().Shutdown();
-#endif
-
     if (mExchangeMgr != nullptr)
     {
         mExchangeMgr->Shutdown();
@@ -483,6 +470,19 @@ void DeviceControllerSystemState::Shutdown()
         // so that SetupController/Commissioner can use it
         mFabrics = nullptr;
     }
+
+#if CONFIG_DEVICE_LAYER
+    //
+    // We can safely call PlatformMgr().Shutdown(), which like DeviceController::Shutdown(),
+    // expects to be called with external thread synchronization and will not try to acquire the
+    // stack lock.
+    //
+    // Actually stopping the event queue is a separable call that applications will have to sequence.
+    // Consumers are expected to call PlaformMgr().StopEventLoopTask() before calling
+    // DeviceController::Shutdown() in the CONFIG_DEVICE_LAYER configuration
+    //
+    DeviceLayer::PlatformMgr().Shutdown();
+#endif
 }
 
 } // namespace Controller