UPSTREAM: crypto: blake2s - implement generic shash driver

Wire up our newly added Blake2s implementation via the shash API.

Bug: 152722841
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I115c2963e90a1a1d2734865d8a2c2e6df5008537