I chose not to optimize smaller than block size of 256 bytes, since XTS is
practically always used with data blocks of size 512 bytes. This is why
performance is reduced in tcrypt for 64 byte long blocks.
Cc: Huang Ying <ying.huang@intel.com> Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>