Don't set accel watch on suspend_cancel unless we're in a state where it has meaning

diff -r 1d647ef26f3f drivers/xen/netfront/accel.c
--- a/drivers/xen/netfront/accel.c
+++ b/drivers/xen/netfront/accel.c
@@ -709,8 +709,9 @@ int netfront_accelerator_suspend_cancel(
 	 * accelerator, so no need to call accelerator_probe_new_vif()
 	 * directly here
 	 */
-	netfront_accelerator_add_watch(np);
- 	return 0;
+	if (dev->state == XenbusStateConnected)
+		netfront_accelerator_add_watch(np);
+	return 0;
 }