usb: otg: nop: fix oops triggered by otg_register_notifier

This patch adds BLOCKING_INIT_NOTIFIER_HEAD in nop_usb_xceiv_probe,
so that we can avoid oops caused by uninitialized
nop->otg.notifier.rwsem which will be touched in otg_register_notifier
path.
Reported-by: Gupta, Ajay Kumar <ajay.gupta@ti.com>
Tested-by: Gupta, Ajay Kumar <ajay.gupta@ti.com>
Cc: Balbi, Felipe <balbi@ti.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/otg/nop-usb-xceiv.c

@@ -132,6 +132,8 @@ static int __devinit nop_usb_xceiv_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, nop);
 
+	BLOCKING_INIT_NOTIFIER_HEAD(&nop->otg.notifier);
+
 	return 0;
 exit:
 	kfree(nop);