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>

drivers/crypto/allwinner/sun8i-ss/sun8i-ss-prng.c

@@ -103,7 +103,8 @@ int sun8i_ss_prng_generate(struct crypto_rng *tfm, const u8 *src,
 	dma_iv = dma_map_single(ss->dev, ctx->seed, ctx->slen, DMA_TO_DEVICE);
 	if (dma_mapping_error(ss->dev, dma_iv)) {
 		dev_err(ss->dev, "Cannot DMA MAP IV\n");
-		return -EFAULT;
+		err = -EFAULT;
+		goto err_free;
 	}
 
 	dma_dst = dma_map_single(ss->dev, d, todo, DMA_FROM_DEVICE);
@@ -167,6 +168,7 @@ int sun8i_ss_prng_generate(struct crypto_rng *tfm, const u8 *src,
 		memcpy(ctx->seed, d + dlen, ctx->slen);
 	}
 	memzero_explicit(d, todo);
+err_free:
 	kfree(d);
 
 	return err;