Document EVP_CIPHER failure for missing provider function

Document EVP_CIPHER failure for missing provider function

When writing a new CIPHER implementation the OSSL_FUNC_cipher_get_params
must be present, otherwise the fetch fails. This behaviour is seen in
function evp_cipher_cache_constants@crypto/evp/evp_lib.c.

Resolves: #25801

Signed-off-by: Norbert Pocs <norbertp@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/27696)