crypto: sun4i-ss - initialize need_fallback

The need_fallback is never initialized and seem to be always true at runtime.
So all hardware operations are always bypassed.

Fixes: 0ae1f46c ("crypto: sun4i-ss - fallback when length is not multiple of blocksize")
Cc: <stable@vger.kernel.org>
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>