Any change to the result buffer should only happen on final, finup
and digest operations. Changes to the buffer for update, import, export,
etc, are not allowed.

Fixes: 66d7b9f6175e ("crypto: testmgr - test misuse of result in ahash")
Signed-off-by: Gary R Hook <gary.hook@amd.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>