[Model] Use static hidden size in mixtral scatter_output

python/mlc_llm/op/moe_misc.py

@@ -385,11 +385,11 @@ def scatter_output(x: Tensor, indices: Tensor) -> Tensor:
         The output of MoE experts with shape [batch_size * num_experts_per_tok, hidden_size].
     """
     dtype = x.dtype
+    _, hidden_size = x.shape
 
     @T.prim_func(private=True)
     def _func(var_x: T.handle, var_indices: T.handle, var_out: T.handle):
         T.func_attr({"tir.noalias": True})
-        hidden_size = T.int64()
         indices_len = T.int64()
         x = T.match_buffer(var_x, [indices_len, hidden_size], dtype)
         indices = T.match_buffer(var_indices, [indices_len], "int32")