Don't (re-)initialize the FFC_PARAMs in dh_init and dsa_init

The initialization was introduced in commit dc8de3e6 and
changes the behaviour of the `init` method for DSA and DH
between 1.1.1 and 3.0, while the behaviour for RSA and EC_KEY
remains unchanged.

The initialization is not necessary in 3.x and master imho and
breaks the use-case of intercepting the methods of an existing
key.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22185)

(cherry picked from commit 706512ec)