typo clip grad without fp16

Author: Mathilde Caron

main_dino.py

@@ -313,7 +313,7 @@ def train_one_epoch(student, teacher, teacher_without_ddp, dino_loss, data_loade
         if fp16_scaler is None:
             loss.backward()
             if args.clip_grad:
-                param_norms = utils.clip_gradients(model, args.clip_grad)
+                param_norms = utils.clip_gradients(student, args.clip_grad)
             utils.cancel_gradients_last_layer(epoch, student,
                                               args.freeze_last_layer)
             optimizer.step()