lib/crypto: s390/aes: Migrate optimized code into library

lib/crypto: s390/aes: Migrate optimized code into library

Implement aes_preparekey_arch(), aes_encrypt_arch(), and
aes_decrypt_arch() using the CPACF AES instructions.

Then, remove the superseded "aes-s390" crypto_cipher.

The result is that both the AES library and crypto_cipher APIs use the
CPACF AES instructions, whereas previously only crypto_cipher did (and
it wasn't enabled by default, which this commit fixes as well).

Note that this preserves the optimization where the AES key is stored in
raw form rather than expanded form.  CPACF just takes the raw key.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Holger Dengler <dengler@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Link: https://lore.kernel.org/r/20260112192035.10427-16-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>