Add a check for is_sagemaker_mp when setting _n_gpu again. Should be last broken thing

Author: muellerzr

src/transformers/training_args.py

@@ -1649,8 +1649,9 @@ def _setup_devices(self) -> "torch.device":
         if is_torch_tpu_available():
             device = self.distributed_state.device
             self._n_gpu = 0
-        elif is_sagemaker_dp_enabled():
-            self._n_gpu = 1
+        elif is_sagemaker_dp_enabled() or is_sagemaker_mp_enabled():
+            # Already set _n_gpu
+            pass
         elif self.distributed_state.distributed_type == DistributedType.NO:
             if self.use_mps_device:
                 if not torch.backends.mps.is_available():