crypto: sun8i-ss - Fix memory leak of object d when dma_iv fails to map

In the case where the dma_iv mapping fails, the return error path leaks
the memory allocated to object d.  Fix this by adding a new error return
label and jumping to this to ensure d is free'd before the return.

Addresses-Coverity: ("Resource leak")
Fixes: ac2614d7 ("crypto: sun8i-ss - Add support for the PRNG")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Acked-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>