[fx] refactored the file structure of patched function and module (#1238)

* [fx] refactored the file structure of patched function and module

* polish code

colossalai/fx/tracer/meta_patch/patched_module/embedding.py

@@ -0,0 +1,8 @@
+import torch
+from ..registry import meta_patched_module
+
+
+@meta_patched_module.register(torch.nn.Embedding)
+def torch_nn_embedding(self, input):
+    result_shape = input.shape + (self.embedding_dim,)
+    return torch.empty(result_shape, device='meta')