Add PKEY_CTX setter tests for TLS1-PRF

PKEY_CTX setters tests were previously present for HKDF and scrypt; this
patch also adds tests for the third currently supported KDF, TLS1-PRF.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4196)