Fix CipherInit on s390x.

Various different initialization sequences led to bugs on s390x due to caching
and processing during key setting.  Since, e.g., the direction does not
necessarily have to be correct during initialization, this produced bugs in
s390x which were not present on other architectures.  Fix this by recomputing
the function codes on the fly during updates and final operations.

Signed-off-by: Juergen Christ <jchrist@linux.ibm.com>

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15521)
