crypto: jitter - Mark intermediary memory as clean

This is not a leak! The stack memroy is hashed and fed into the
entropy pool. We can't recover the original kernel memory from it.

Reported-by:  <syzbot+e8bcd7ee3db6cb5cb875@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=e8bcd7ee3db6cb5cb875


Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>