bugfix for npu not support float64 (#10123)

* bugfix for npu not support float64

* is_mps is_npu

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Co-authored-by: 白超 <baichao19@huawei.com>
Co-authored-by: hlky <hlky@hlky.ac>

src/diffusers/pipelines/pixart_alpha/pipeline_pixart_sigma.py

@@ -822,10 +822,11 @@ class PixArtSigmaPipeline(DiffusionPipeline):
                     # TODO: this requires sync between CPU and GPU. So try to pass timesteps as tensors if you can
                     # This would be a good case for the `match` statement (Python 3.10+)
                     is_mps = latent_model_input.device.type == "mps"
+                    is_npu = latent_model_input.device.type == "npu"
                     if isinstance(current_timestep, float):
-                        dtype = torch.float32 if is_mps else torch.float64
+                        dtype = torch.float32 if (is_mps or is_npu) else torch.float64
                     else:
-                        dtype = torch.int32 if is_mps else torch.int64
+                        dtype = torch.int32 if (is_mps or is_npu) else torch.int64
                     current_timestep = torch.tensor([current_timestep], dtype=dtype, device=latent_model_input.device)
                 elif len(current_timestep.shape) == 0:
                     current_timestep = current_timestep[None].to(latent_model_input.device)