[CDFS_NEW] Address review comments:

- Don't define-out volatile.
- Cleanup the ros-specific hdd-backed device object on shutdown.
- Fix hdd-backed use. Required a rather ugly hack.
- Update README.FSD

drivers/filesystems/cdfs_new/shutdown.c

@@ -167,6 +167,10 @@ Return Value:
 
     IoUnregisterFileSystem( CdData.FileSystemDeviceObject );
     IoDeleteDevice( CdData.FileSystemDeviceObject );
+#ifdef __REACTOS__
+    IoUnregisterFileSystem( CdData.HddFileSystemDeviceObject );
+    IoDeleteDevice( CdData.HddFileSystemDeviceObject );
+#endif
 
     CdCompleteRequest( IrpContext, Irp, STATUS_SUCCESS );
     return STATUS_SUCCESS;