Improve vector FP16 comparison function

[r-devulap]

I suspect this function https://github.com/intel/x86-simd-sort/blob/7d7591cf5927e83e4a1e7c4b6f2c4dc91a97889f/src/avx512-16bit-qsort.hpp#L65 can be improved with fewer operations. See: https://github.com/numpy/numpy/blob/0bd56e7ec12f8ceeb8d082340e71e60b873d5c57/numpy/core/src/npysort/npysort_common.h#L153 for reference.