fix: remove unused device type placeholders

[voltjia]

Summary

• Remove unsupported kKunlun and kQy device type placeholders from Device::Type.
• Remove their string mappings and AllDeviceTypes entries so the active device list only covers implemented backends.

Motivation

Kunlun and Qy do not have CMake options, generated public-header mappings, or native runtime/device implementations yet. Keeping them in the public device enum makes them look supported before the backend support exists.

Smoke Build / Test Evidence

• rg -n "kKunlun|kQy|kunlun|qy" . returned no matches after the change.
• git diff --check passed.
• python -m py_compile scripts/generate_public_headers.py passed using the bundled Python runtime.
• python scripts/generate_public_headers.py --output-dir build/generated-check/include --source-output build/generated-check/runtime_dispatch.cc --devices cpu nvidia iluvatar hygon metax moore cambricon ascend passed.

Not Run

• cmake -S . -B build -DWITH_CPU=ON -DINFINI_RT_BUILD_TESTING=ON because cmake is not installed in this local environment.

Risk

Low. This only removes public enum/string/list entries for backends that are not otherwise wired into the build or generated-header path.