Disable SHA3 s390x acceleration for CSHAKE
* cipher/keccak.c (keccak_final_s390x): Add assert check for expected SHAKE suffix. (_gcry_cshake_customize, cshake_hash_buffers): Disable s390x acceleration when selecting CSHAKE suffix.
- Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>