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: openssl#25801

Signed-off-by: Norbert Pocs <[email protected]>

Reviewed-by: Paul Dale <[email protected]>
Reviewed-by: Matt Caswell <[email protected]>
(Merged from openssl#27696)

Author: jogme

doc/man7/provider-cipher.pod

@@ -134,8 +134,8 @@ In order to be a consistent set of functions there must at least be a complete
 set of "encrypt" functions, or a complete set of "decrypt" functions, or a
 single "cipher" function. Similarly, there can be a complete set of pipeline
 "encrypt" functions, and/or a complete set of pipeline "decrypt" functions.
-In all cases both the OSSL_FUNC_cipher_newctx and OSSL_FUNC_cipher_freectx functions must be
-present.
+In all cases the OSSL_FUNC_cipher_get_params and both OSSL_FUNC_cipher_newctx
+and OSSL_FUNC_cipher_freectx functions must be present.
 All other functions are optional.
 
 =head2 Context Management Functions