Revert 2 PRs for quant fix (#484)

Revert
#480
#481

Author: vadiklyutiy

python/hidet/graph/ops/quant/symmetric.py

@@ -12,7 +12,6 @@
 from typing import Union, List
 from hidet import ir
 from hidet.ir.type import DataType
-from hidet.ir.dtypes import int32
 from hidet.ir.expr import cast, if_then_else
 from hidet.ir.compute.primitives import TensorNode, compute
 from hidet.ir import primitives as prim
@@ -37,9 +36,7 @@ def __init__(self, w: TensorNode, quant_type: DataType, dims: Union[int, List[in
 
         def scale_weight(*indices):
             scale_indices = [indices[i] for i in range(len(indices)) if not i in dims]
-            # Have to cast to int32 first because there are several ways convert bf16 to int8
-            cast_to_int = cast(prim.round(w[indices] / scale[scale_indices]), int32)
-            return cast(cast_to_int, quant_type)
+            return cast(prim.round(w[indices] / scale[scale_indices]), quant_type)
 
         wq = compute(name='quantize', shape=w.shape, fcompute=scale_weight)
         super().__init__(