crypto: sun8i-ss - fix removal of module

Removing the driver cause an oops due to the fact we clean an extra
channel.
Let's give the right index to the cleaning function.
Fixes: f08fcced ("crypto: allwinner - Add sun8i-ss cryptographic offloader")

Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>