usb: renesas_usbhs: remove callback when module removed.

The callback function which is called from platform must be removed
if module removed.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/renesas_usbhs/common.c b/drivers/usb/renesas_usbhs/common.c
index d9ad60d..fda586d 100644
--- a/drivers/usb/renesas_usbhs/common.c
+++ b/drivers/usb/renesas_usbhs/common.c
@@ -352,9 +352,13 @@
 static int __devexit usbhs_remove(struct platform_device *pdev)
 {
 	struct usbhs_priv *priv = usbhsc_pdev_to_priv(pdev);
+	struct renesas_usbhs_platform_info *info = pdev->dev.platform_data;
+	struct renesas_usbhs_driver_callback *dfunc = &info->driver_callback;
 
 	dev_dbg(&pdev->dev, "usb remove\n");
 
+	dfunc->notify_hotplug = NULL;
+
 	pm_runtime_disable(&pdev->dev);
 
 	usbhsc_bus_ctrl(priv, 0);