[media] m2m-deinterlace: use correct check for kzalloc failure

There is no point in PTR_ERR()ing a NULL pointer, use a real error
instead.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/platform/m2m-deinterlace.c

@@ -917,10 +917,8 @@ static int deinterlace_open(struct file *file)
 	ctx->xt = kzalloc(sizeof(struct dma_async_tx_descriptor) +
 				sizeof(struct data_chunk), GFP_KERNEL);
 	if (!ctx->xt) {
-		int ret = PTR_ERR(ctx->xt);
-
 		kfree(ctx);
-		return ret;
+		return -ENOMEM;
 	}
 
 	ctx->colorspace = V4L2_COLORSPACE_REC709;