Revert "Fix bug in EVP_CIPHER_CTX_get_iv_length()"

This reverts commit f428e211.

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/18946)