doc: add return value documentation for EVP_CIPHER_*_params functions

doc: add return value documentation for EVP_CIPHER_*_params functions

Document that EVP_CIPHER_get_params(), EVP_CIPHER_CTX_get_params() and
EVP_CIPHER_CTX_set_params() return 1 for success and 0 for failure.

Fixes #29725

CLA: trivial

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Eugene Syromiatnikov <esyr@openssl.org>
MergeDate: Tue Feb  3 09:51:47 2026
(Merged from https://github.com/openssl/openssl/pull/29779)