usb: dwc3: st: Add of_node_put() before return in probe function

The local variable child in the function st_dwc3_probe takes the return
value of of_get_child_by_name, which gets a node and does not put it. If
the function returns without releasing child, this could cause a memory
error. Hence put child as soon as there is no more use for it. Also
create a new label, err_node_put, just before label undo_softreset; so
that err_node_put puts child. In between initialisation of child and its
first put, modify all statements that go to undo_softreset to now go to
err_node_put instead, from where they can fall through to
undo_softreset.
Issue found with Coccinelle.
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/dwc3-st.c

@@ -255,24 +255,25 @@ static int st_dwc3_probe(struct platform_device *pdev)
 	if (!child) {
 		dev_err(&pdev->dev, "failed to find dwc3 core node\n");
 		ret = -ENODEV;
-		goto undo_softreset;
+		goto err_node_put;
 	}
 
 	/* Allocate and initialize the core */
 	ret = of_platform_populate(node, NULL, NULL, dev);
 	if (ret) {
 		dev_err(dev, "failed to add dwc3 core\n");
-		goto undo_softreset;
+		goto err_node_put;
 	}
 
 	child_pdev = of_find_device_by_node(child);
 	if (!child_pdev) {
 		dev_err(dev, "failed to find dwc3 core device\n");
 		ret = -ENODEV;
-		goto undo_softreset;
+		goto err_node_put;
 	}
 
 	dwc3_data->dr_mode = usb_get_dr_mode(&child_pdev->dev);
+	of_node_put(child);
 
 	/*
 	 * Configure the USB port as device or host according to the static
@@ -292,6 +293,8 @@ static int st_dwc3_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, dwc3_data);
 	return 0;
 
+err_node_put:
+	of_node_put(child);
 undo_softreset:
 	reset_control_assert(dwc3_data->rstc_rst);
 undo_powerdown: