crypto: blake2s: remove module-related code

Now blake2s-generic.c can no longer be a module, drop all remaining
module-related code as well.

Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Requested-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: linux-modules@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Hitomi Hasegawa <hasegawa-hitomi@fujitsu.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>