crypto: testmgr - Add testing for async hashing and update/final

Extend testmgr such that it tests async hash algorithms,
and that for both sync and async hashes it tests both
->digest() and ->update()/->final() sequences.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>