Currently, we rely on the generic CTS chaining mode wrapper to
instantiate the cts(cbc(aes)) skcipher. Due to the high performance
of the ARMv8 Crypto Extensions AES instructions (~1 cycles per byte),
any overhead in the chaining mode layers is amplified, and so it pays
off considerably to fold the CTS handling into the SIMD routines.

On Cortex-A53, this results in a ~50% speedup for smaller input sizes.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>