crypto: sun8i-ce - fix error return code in sun8i_ce_prng_generate()

When dma_mapping_error() returns an error, no error return code of
sun8i_ce_prng_generate() is assigned.
To fix this bug, err is assigned with -EFAULT as error return code.
Reported-by: NTOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: NJia-Ju Bai <baijiaju1990@gmail.com>
Tested-by: NCorentin Labbe <clabbe.montjoie@gmail.com>
Acked-by: NCorentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

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

@@ -99,6 +99,7 @@ int sun8i_ce_prng_generate(struct crypto_rng *tfm, const u8 *src,
 	dma_iv = dma_map_single(ce->dev, ctx->seed, ctx->slen, DMA_TO_DEVICE);
 	if (dma_mapping_error(ce->dev, dma_iv)) {
 		dev_err(ce->dev, "Cannot DMA MAP IV\n");
+		err = -EFAULT;
 		goto err_iv;
 	}