crypto: sun4i-ss - checking sg length is not sufficient

The optimized cipher function need length multiple of 4 bytes.
But it get sometimes odd length.
This is due to SG data could be stored with an offset.

So the fix is to check also if the offset is aligned with 4 bytes.
Fixes: 6298e948 ("crypto: sunxi-ss - Add Allwinner Security System crypto accelerator")
Cc: <stable@vger.kernel.org>
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>