Revert "Refactor llama family models (#2637)" (#2851)

This reverts commit 5c976a7e1a.

vllm/model_executor/layers/layernorm.py

@@ -7,31 +7,6 @@ import torch.nn as nn
 from vllm._C import ops
 
 
-class LayerNorm(nn.LayerNorm):
-
-    def __init__(
-        self,
-        hidden_size: int,
-        eps: float = 1e-6,
-    ) -> None:
-        super().__init__(hidden_size, eps=eps)
-
-    def forward(
-        self,
-        x: torch.Tensor,
-        residual: Optional[torch.Tensor] = None,
-    ) -> Union[torch.Tensor, Tuple[torch.Tensor, torch.Tensor]]:
-        """normalization."""
-        if residual is not None:
-            x = x + residual
-            residual = x
-        x = super().forward(x)
-        if residual is None:
-            return x
-        else:
-            return x, residual
-
-
 class RMSNorm(nn.Module):
     """Root mean square normalization.