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>