Fix quark quantization PHX/HPT NPU options

[Rohithmatham12]

Summary\n- Align quark_quantization benchmark VitisAI EP cache options with the working int8 ResNet predict path by using cache_dir/cache_key.\n- Set xlnx_enable_py3_round=0 for PHX/HPT alongside the required target and xclbin options.\n- Update the README NPU provider-options snippet so users copy the same option style.\n\nWhy\nIssue #376 reports that CNN-examples/quark_quantization/quark_quantize.py falls back to CPU on PHX/HPT while the same quantized model runs on the NPU through CNN-examples/getting_started_resnet/int8/predict.py. The benchmark path was using different provider option keys and missing the PHX/HPT rounding option used by the working path.\n\nTesting\n- python3 -m py_compile CNN-examples/quark_quantization/quark_quantize.py CNN-examples/quark_quantization/utils.py\n- git diff --check\n\nNot run locally: PHX/HPT NPU benchmark validation, because this machine does not have Ryzen AI hardware/XRT.\n\nFixes #376