Fix async_io ops building error on Huawei Ascend NPU (#7894)

### Summary

Fixes async_io ops building error on Huawei Ascend NPU.

### Environment

| Item                       | Version            |
| -------------------------- | ------------------ |
| kernel version             | 5.15.0-101-generic |
| torch version              | 2.8.0+cpu          |
| deepspeed info             | 0.18.7             |
| deepspeed wheel compiled w | torch 2.8          |
| torch_npu version          | 2.8.0              |
| ascend_cann version        | 8.1.RC1            |

Deepspeed config "zero_optimization.offload_optimizer.device" = "nvme"
(device = "cpu" works).

### Error Messages

When offloading from NPU to NVME, error occurs:

```text
ImportError: /.../async_io.so: undefined symbol: _ZN21deepspeed_io_handle_t18_create_io_op_descEbRKN2at6TensorEiPKcbl
```

nm tells that the symbol is declared but not defined, but it's found at
"csrc/aio/py_lib/deepspeed_py_io_handle.cpp":

```sh
nm async_io.so | rg _ZN21deepspeed_io_handle_t18_create_io_op_descEbRKN2at6TensorEiPKcbl
#                 U _ZN21deepspeed_io_handle_t18_create_io_op_descEbRKN2at6TensorEiPKcbl
```

# Solution

1. `op_builder/npu/async_io.py`:

```python
class AsyncIOBuilder(NPUOpBuilder):
    def sources(self):
        return [
            'csrc/aio/py_lib/deepspeed_py_copy.cpp', 'csrc/aio/py_lib/py_ds_aio.cpp',
            'csrc/aio/py_lib/deepspeed_py_aio.cpp', 'csrc/aio/py_lib/deepspeed_py_aio_handle.cpp',
            'csrc/aio/py_lib/deepspeed_aio_thread.cpp', 'csrc/aio/common/deepspeed_aio_utils.cpp',
            'csrc/aio/common/deepspeed_aio_common.cpp', 'csrc/aio/common/deepspeed_aio_types.cpp',
            'csrc/aio/py_lib/deepspeed_pin_tensor.cpp',
            # Adds 3 source files:
            'csrc/aio/py_lib/deepspeed_py_io_handle.cpp',
            'csrc/aio/py_lib/deepspeed_aio_op_desc.cpp',
            'csrc/aio/py_lib/deepspeed_cpu_op.cpp'
        ]
```

2. `csrc/aio/py_lib/deepspeed_cpu_op.cpp`:

```cpp
#if defined(__ENABLE_CANN__)
            // `DS_BUILD_OPS=1 install.sh` complains that ‘torch_npu’ has not
            // been declared, so inlines `torch_npu::utils::is_npu`.
            if (_buffer.is_privateuseone()) {
                auto device = at::Device("npu:0");
                _buffer.copy_(_cpu_buffer.to(device));
            }
#endif
```

Signed-off-by: Huang Yifan <yifan0610@foxmail.com>
Co-authored-by: Olatunji Ruwase <tunji.ruwase@snowflake.com>

Author: huangyifan0610

csrc/aio/py_lib/deepspeed_cpu_op.cpp

@@ -45,7 +45,9 @@ void cpu_op_desc_t::finish()
             if (_buffer.is_xpu()) { _buffer.copy_(_cpu_buffer.to(torch::kXPU)); }
             if (_buffer.is_cpu()) { _buffer.copy_(_cpu_buffer); }
 #if defined(__ENABLE_CANN__)
-            if (torch_npu::utils::is_npu(_buffer)) {
+            // `DS_BUILD_OPS=1 install.sh` complains that ‘torch_npu’ has not
+            // been declared, so inline `torch_npu::utils::is_npu`.
+            if (_buffer.is_privateuseone()) {
                 auto device = at::Device("npu:0");
                 _buffer.copy_(_cpu_buffer.to(device));
             }

op_builder/npu/async_io.py

@@ -25,7 +25,8 @@ def sources(self):
             'csrc/aio/py_lib/deepspeed_py_aio.cpp', 'csrc/aio/py_lib/deepspeed_py_aio_handle.cpp',
             'csrc/aio/py_lib/deepspeed_aio_thread.cpp', 'csrc/aio/common/deepspeed_aio_utils.cpp',
             'csrc/aio/common/deepspeed_aio_common.cpp', 'csrc/aio/common/deepspeed_aio_types.cpp',
-            'csrc/aio/py_lib/deepspeed_pin_tensor.cpp'
+            'csrc/aio/py_lib/deepspeed_pin_tensor.cpp', 'csrc/aio/py_lib/deepspeed_py_io_handle.cpp',
+            'csrc/aio/py_lib/deepspeed_aio_op_desc.cpp', 'csrc/aio/py_lib/deepspeed_cpu_op.cpp'
         ]
 
     def include_paths(self):