[media] davinci: vpif: fix return value check for vb2_dma_contig_init_ctx()

In case of error, the function vb2_dma_contig_init_ctx() returns
ERR_PTR() and never returns NULL. The NULL test in the return value
check should be replaced with IS_ERR().
dpatch engine is used to auto generate this patch.
(https://github.com/weiyj/dpatch)

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Lad, Prabhakar <prabhakar.lad@ti.com>
[prabhakar.lad@ti.com: reword commit header]
Signed-off-by: Lad, Prabhakar <prabhakar.lad@ti.com>

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/platform/davinci/vpif_capture.c

@@ -1004,9 +1004,9 @@ static int vpif_reqbufs(struct file *file, void *priv,
 
 	/* Initialize videobuf2 queue as per the buffer type */
 	common->alloc_ctx = vb2_dma_contig_init_ctx(vpif_dev);
-	if (!common->alloc_ctx) {
+	if (IS_ERR(common->alloc_ctx)) {
 		vpif_err("Failed to get the context\n");
-		return -EINVAL;
+		return PTR_ERR(common->alloc_ctx);
 	}
 	q = &common->buffer_queue;
 	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

drivers/media/platform/davinci/vpif_display.c

@@ -972,9 +972,9 @@ static int vpif_reqbufs(struct file *file, void *priv,
 	}
 	/* Initialize videobuf2 queue as per the buffer type */
 	common->alloc_ctx = vb2_dma_contig_init_ctx(vpif_dev);
-	if (!common->alloc_ctx) {
+	if (IS_ERR(common->alloc_ctx)) {
 		vpif_err("Failed to get the context\n");
-		return -EINVAL;
+		return PTR_ERR(common->alloc_ctx);
 	}
 	q = &common->buffer_queue;
 	q->type = V4L2_BUF_TYPE_VIDEO_OUTPUT;