crypto: sun4i-ss - hide the Invalid keylen message

Drop the "Invalid keylen" message to debug level, it adds no value, and
when CRYPTO_EXTRA_TEST is enabled, it floods the console.

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