crypto: x86/aesni - Correct the data type in struct aesni_xts_ctx

Currently, every field in struct aesni_xts_ctx is defined as a byte
array of the same size as struct crypto_aes_ctx. This data type
is obscure and the choice lacks justification.

To rectify this, update the field type in struct aesni_xts_ctx to
match its actual structure.

Suggested-by: Eric Biggers <ebiggers@kernel.org>
Link: https://lore.kernel.org/all/ZFWQ4sZEVu%2FLHq+Q@gmail.com/


Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Cc: linux-crypto@vger.kernel.org
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>