LayerNorm example fails on autotuning

[PaulZhang12]

The LayerNorm example #170 currently fails when autotuning, especially when setting the config reduction_loops to anything but None. Specifically, it fails on an assert for codegen for _get_symnode

helion/helion/language/_tracing_ops.py

Line 45 in 41fe6e9

assert isinstance(val, (torch.SymInt, torch.SymFloat, torch.SymBool)), val

, in which val is a constant, 64, which is the reduction dimension.