crypto: sun8i-ss - handle requests if last block is not modulo 64

The current sun8i-ss handle only requests with all SG length being
modulo 64.
But the last SG could be always handled by copying it on the pad buffer.

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