staging: kpc2000: kpc_dma: set error code in probe

If device_create() fails during probing the device, kpc_dma_probe() does
not set the error code and returns 0. This can result in various bad
issues later. The patch sets the error code on the corresponding error
handling path.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Evgeny Novikov <novikov@ispras.ru>
Link: https://lore.kernel.org/r/20200623082959.14951-1-novikov@ispras.ruSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.c

@@ -140,6 +140,7 @@ int  kpc_dma_probe(struct platform_device *pldev)
 	dev = MKDEV(assigned_major_num, pldev->id);
 	ldev->kpc_dma_dev = device_create(kpc_dma_class, &pldev->dev, dev, ldev, "kpc_dma%d", pldev->id);
 	if (IS_ERR(ldev->kpc_dma_dev)) {
+		rv = PTR_ERR(ldev->kpc_dma_dev);
 		dev_err(&ldev->pldev->dev, "%s: device_create failed: %d\n", __func__, rv);
 		goto err_kfree;
 	}