rijndael-aesni: add 8-block parallel code path for XTS
* cipher/rijndael-aesni.c (xts_gfmul_const): Fix array size from 16 to 2. (_gcry_aes_aesni_xts_enc, _gcry_aes_aesni_xts_dec) [__x86_64__]: Add 8-block parallel code paths.
- Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>