iris: Do not call syncobj ioctls if handle is invalid
minor code optimization to save some of cycles: We can skip unnecessary call of syncobj-handle-to-fd or syncobj-fd-to-handle drm-ioctls when arg.handle is invalid.
minor code optimization to save some of cycles: We can skip unnecessary call of syncobj-handle-to-fd or syncobj-fd-to-handle drm-ioctls when arg.handle is invalid.