fix dtype='AUTO' -> 'bf16' bug (#755)

Author: Jintao-Huang

swift/llm/utils/argument.py

@@ -119,7 +119,7 @@ def select_dtype(
                 raise ValueError(f'args.dtype: {self.dtype}')
         # cuda, npu
         if self.dtype == 'AUTO':
-            if is_torch_bf16_gpu_available():
+            if not is_torch_bf16_gpu_available():
                 self.dtype = 'fp16'
             else:
                 model_torch_dtype = MODEL_MAPPING[self.model_type].get(