xen/events: Set irq_info->evtchn before binding the channel to CPU in __startup_pirq()

.. because bind_evtchn_to_cpu(evtchn, cpu) will map evtchn to
'info' and pass 'info' down to xen_evtchn_port_bind_to_cpu().
Signed-off-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Tested-by: NAnnie Li <annie.li@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

drivers/xen/events/events_base.c

@@ -529,8 +529,8 @@ static unsigned int __startup_pirq(unsigned int irq)
 	if (rc)
 		goto err;
 
-	bind_evtchn_to_cpu(evtchn, 0);
 	info->evtchn = evtchn;
+	bind_evtchn_to_cpu(evtchn, 0);
 
 	rc = xen_evtchn_port_setup(info);
 	if (rc)