openssl: PRF_KEYED_SHA1 might not be supported

openssl: PRF_KEYED_SHA1 might not be supported

The old API has been deprecated with OpenSSL 3 and direct access to the
state isn't possible via EVP API.  In the future we might just remove this
implementation but we'd probably have to implement EAP-AKA' first, which
uses HMAC-SHA-256 with IKEv2's prf+ construct to derive keys instead
of this weird construct (plus what fips-prf builds around it) that's used
by EAP-AKA.