crypto: sm3 - create SM3 stand-alone library

Stand-alone implementation of the SM3 algorithm. It is designed
to have as little dependencies as possible. In other cases you
should generally use the hash APIs from include/crypto/hash.h.
Especially when hashing large amounts of data as those APIs may
be hw-accelerated. In the new SM3 stand-alone library,
sm3_transform() has also been optimized, instead of simply using
the code in sm3_generic.

Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Reviewed-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>