crypto: sun4i-ss - IV register does not work on A10 and A13

Allwinner A10 and A13 SoC have a version of the SS which produce
invalid IV in IVx register.

Instead of adding a variant for those, let's convert SS to produce IV
directly from data.
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>