Remove triton_helpers.* usage in lifted device function arguments

[yf225]

Before this PR, the repro unit test fails with:

Traceback (most recent call last):
  File "/home/willfeng/local/helion/repro_helion_452.py", line 47, in <module>
    matmul_bf16_packed_int4(A, B_packed, C)
  File "/home/willfeng/local/helion/helion/runtime/kernel.py", line 286, in __call__
    return self.bind(args)(*args)
           ^^^^^^^^^^^^^^^^^^^^^^
  File "/home/willfeng/local/helion/helion/runtime/kernel.py", line 628, in __call__
    return self._run(*args)
           ^^^^^^^^^^^^^^^^
  File "/tmp/torchinductor_willfeng/zb/czbop2smftqaw2ju36ofqvpvihrlr5qvpuyiqkvfj5n7a75nnrfj.py", line 54, in matmul_bf16_packed_int4
    _launcher(_helion_matmul_bf16_packed_int4, (triton.cdiv(32, _BLOCK_SIZE_2),), B_packed, A, C, _BLOCK_SIZE_2, _BLOCK_SIZE_0, _BLOCK_SIZE_1, triton_helpers.div_floor_integer(_BLOCK_SIZE_1, 2), num_warps=4, num_stages=3)
                                                                                                                                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/willfeng/local/pytorch-nightly/triton/runtime/jit.py", line 868, in __call__
    raise RuntimeError("Cannot call @triton.jit'd outside of the scope of a kernel")
RuntimeError: Cannot call @triton.jit'd outside of the scope of a kernel

because when we lift _BLOCK_SIZE_1 // 2 to become device function argument, it shows up as triton_helpers.div_floor_integer(_BLOCK_SIZE_1, 2), and triton_helpers.* functions are not available outside of Triton kernel.

Closes #452.