crypto: rockchip - remove non-aligned handling

Now driver have fallback for un-aligned cases, remove all code handling
those cases.

Fixes: ce0183cb ("crypto: rockchip - switch to skcipher API")
Reviewed-by: John Keeping <john@metanate.com>
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>