[PATCH -next] mtd: nand: sunxi: fix return value check in sunxi_nfc_dma_op_prepare()

[weiyj_lk]

From: Wei Yongjun <yongjun_...@trendmicro.com.cn>

In case of error, the function dmaengine_prep_slave_sg() returns NULL
pointer not ERR_PTR(). The IS_ERR() test in the return value check
should be replaced with NULL test.

Signed-off-by: Wei Yongjun <yongjun_...@trendmicro.com.cn>
---
 drivers/mtd/nand/sunxi_nand.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
index ef7f6df..653cb3a 100644
--- a/drivers/mtd/nand/sunxi_nand.c
+++ b/drivers/mtd/nand/sunxi_nand.c
@@ -390,8 +390,8 @@ static int sunxi_nfc_dma_op_prepare(struct mtd_info *mtd, 
const void *buf,
                return -ENOMEM;
 
        dmad = dmaengine_prep_slave_sg(nfc->dmac, sg, 1, tdir, DMA_CTRL_ACK);
-       if (IS_ERR(dmad)) {
-               ret = PTR_ERR(dmad);
+       if (!dmad) {
+               ret = -EINVAL;
                goto err_unmap_buf;
        }