crypto: sha256 - Create module providing optimized SHA256 routines using SSSE3, AVX or AVX2 instructions.

We added glue code and config options to create crypto
module that uses SSE/AVX/AVX2 optimized SHA256 x86_64 assembly routines.
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>