[Defect]: Variant pattern for PBKDF2 must have {prfFunction} instead of {hashAlgorithm}

## Describe the defect

As per the [SP800-132](https://doi.org/10.6028/NIST.SP.800-132), PBKDF2 is the PBKDF using HMAC with any approved hash function as the PRF. Therefore, the variable {prfFunction} must be an element of the variant pattern instead of {hashAlgorithm}.

## Additional context

The issue is data-quality / naming defect in the Cryptography Registry and can be fixed without changing schema behavior or introducing new algorithms.