crypto: sha256-mb - SHA256 multibuffer job manager and glue code

This patch introduces the multi-buffer job manager which is responsible for
submitting scatter-gather buffers from several SHA256 jobs to the
multi-buffer algorithm. It also contains the flush routine to that's
called by the crypto daemon to complete the job when no new jobs arrive
before the deadline of maximum latency of a SHA256 crypto job.

The SHA256 multi-buffer crypto algorithm is defined and initialized in
this patch.

Signed-off-by: Megha Dey <megha.dey@linux.intel.com>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>