OHCI: Fix machine check in ohci_hub_status_data

This patch (as901) fixes an oversight in ohci-hcd.  The
hub_status_data routine must not try to access the controller's
memory-mapped registers if the controller is in a low-power state;
such attempts will cause a crash on some architectures (such as PPC).
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/ohci-hub.c

@@ -417,6 +417,8 @@ ohci_hub_status_data (struct usb_hcd *hcd, char *buf)
 	unsigned long	flags;
 
 	spin_lock_irqsave (&ohci->lock, flags);
+	if (!test_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags))
+		goto done;
 
 	/* undocumented erratum seen on at least rev D */
 	if ((ohci->flags & OHCI_QUIRK_AMD756)