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

The initialization was introduced in commit dc8de3e 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 #22185)

(cherry picked from commit 706512e)

crypto/dh/dh_key.c

@@ -190,7 +190,6 @@ static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
 static int dh_init(DH *dh)
 {
     dh->flags |= DH_FLAG_CACHE_MONT_P;
-    ossl_ffc_params_init(&dh->params);
     dh->dirty_cnt++;
     return 1;
 }

crypto/dh/dh_lib.c

@@ -116,6 +116,8 @@ static DH *dh_new_intern(ENGINE *engine, OSSL_LIB_CTX *libctx)
         goto err;
 #endif /* FIPS_MODULE */
 
+    ossl_ffc_params_init(&ret->params);
+
     if ((ret->meth->init != NULL) && !ret->meth->init(ret)) {
         ERR_raise(ERR_LIB_DH, ERR_R_INIT_FAIL);
         goto err;

crypto/dsa/dsa_lib.c

@@ -176,6 +176,8 @@ static DSA *dsa_new_intern(ENGINE *engine, OSSL_LIB_CTX *libctx)
         goto err;
 #endif
 
+    ossl_ffc_params_init(&ret->params);
+
     if ((ret->meth->init != NULL) && !ret->meth->init(ret)) {
         ERR_raise(ERR_LIB_DSA, ERR_R_INIT_FAIL);
         goto err;

crypto/dsa/dsa_ossl.c

@@ -441,7 +441,6 @@ static int dsa_do_verify(const unsigned char *dgst, int dgst_len,
 static int dsa_init(DSA *dsa)
 {
     dsa->flags |= DSA_FLAG_CACHE_MONT_P;
-    ossl_ffc_params_init(&dsa->params);
     dsa->dirty_cnt++;
     return 1;
 }