net: mvmdio: do not clk_disable_unprepare() NULL clock

There is no need to clk_disable_unprepare(dev->clk)
before it was initialized.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/mvmdio.c

@@ -211,8 +211,7 @@ static int orion_mdio_probe(struct platform_device *pdev)
 	dev->regs = devm_ioremap(&pdev->dev, r->start, resource_size(r));
 	if (!dev->regs) {
 		dev_err(&pdev->dev, "Unable to remap SMI register\n");
-		ret = -ENODEV;
-		goto out_mdio;
+		return -ENODEV;
 	}
 
 	init_waitqueue_head(&dev->smi_busy_wait);