USB: avoid urb->pipe in usbmon

This patch (as949) changes the usbmon driver to use the new urb->ep
field rather than urb->pipe.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>