dmaengine: ioat: set error code on failures

In function ioat_dma_self_test(), when the calls to dma_mapping_error()
fails, the value of return variable err is 0 (indicates no error). As a
result, the return value may be inconsistent with the execution status.
This patch fixes the bug by assigning -ENOMEM to err on the error path.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=188591
Signed-off-by: Pan Bian <bianpan2016@163.com>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/ioat/init.c

@@ -340,11 +340,13 @@ static int ioat_dma_self_test(struct ioatdma_device *ioat_dma)
 	dma_src = dma_map_single(dev, src, IOAT_TEST_SIZE, DMA_TO_DEVICE);
 	if (dma_mapping_error(dev, dma_src)) {
 		dev_err(dev, "mapping src buffer failed\n");
+		err = -ENOMEM;
 		goto free_resources;
 	}
 	dma_dest = dma_map_single(dev, dest, IOAT_TEST_SIZE, DMA_FROM_DEVICE);
 	if (dma_mapping_error(dev, dma_dest)) {
 		dev_err(dev, "mapping dest buffer failed\n");
+		err = -ENOMEM;
 		goto unmap_src;
 	}
 	flags = DMA_PREP_INTERRUPT;