CPU benchmarks allow for `algorithm` parameter

[coezmaden]

Currently CPU benchmarks allow for the algorithm parameter, which means the same code is tested multiple times, although it's the same code.

KernelAlgorithm distinction should only influence GPU benchmarks.

[coezmaden]

Current workaround: comment out any other algorithm names except one. Algorithm names are irrelevant on CPU. The solving of this issue would require nested parameters.