[OpenCL] Nvidia incorrectly report the absence 64-bit atomic operation

[kif]

This creates a useless warning. Within OpenCL code, the extension is working. TODO: write a small opencl program which checks the actual presence of the extension and report if the extension is working or not.

[kif]

Maybe part of silx rather than pyFAI

[kif]

Finally nvidia not advertizing a feature it better than AMD advertizing unsupported feature !

[kif]

Done in: https://github.com/silx-kit/silx/blob/main/src/silx/opencl/common.py#L453