usb: chipidea: prevent endless loop registering platform_devices when probe fails

Commit 40dcd0e ("usb: chipidea: add PTW, PTS and STS handling") introduced
the following code to the ci_hdrc_probe() function:

+       if (!dev->of_node && dev->parent)
+               dev->of_node = dev->parent->of_node;

This inadvertently associates the ci_hdrc device with the ci_hdrc_imx
driver (which created the ci_hdrc device in the first place).

This results in ci_hdrc_imx_probe() being run for the ci_hdrc device
if ci_hdrc_probe() fails for some reason.
ci_hdrc_imx_probe() will happily create a new ci_hdrc platform_device
whose probing will likewise fail and trigger a new invocation of
ci_hdrc_imx_probe() ... ad nauseam.

Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
Reviewed-and-tested-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/chipidea/core.c

@@ -404,15 +404,13 @@ static int ci_hdrc_probe(struct platform_device *pdev)
 	void __iomem	*base;
 	int		ret;
 	enum usb_dr_mode dr_mode;
+	struct device_node *of_node = dev->of_node ?: dev->parent->of_node;
 
 	if (!dev->platform_data) {
 		dev_err(dev, "platform data missing\n");
 		return -ENODEV;
 	}
 
-	if (!dev->of_node && dev->parent)
-		dev->of_node = dev->parent->of_node;
-
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	base = devm_ioremap_resource(dev, res);
 	if (IS_ERR(base))
@@ -453,12 +451,12 @@ static int ci_hdrc_probe(struct platform_device *pdev)
 	}
 
 	if (!ci->platdata->phy_mode)
-		ci->platdata->phy_mode = of_usb_get_phy_mode(dev->of_node);
+		ci->platdata->phy_mode = of_usb_get_phy_mode(of_node);
 
 	hw_phymode_configure(ci);
 
 	if (!ci->platdata->dr_mode)
-		ci->platdata->dr_mode = of_usb_get_dr_mode(dev->of_node);
+		ci->platdata->dr_mode = of_usb_get_dr_mode(of_node);
 
 	if (ci->platdata->dr_mode == USB_DR_MODE_UNKNOWN)
 		ci->platdata->dr_mode = USB_DR_MODE_OTG;