usb: Based on a 2.4 patch from John_Hull@Dell.com, this patch
     serializes usb storage and usbfs operation, so that usbfs
     cannot disturb storage by seemingly harmless control reads.
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>