use the new async probing feature for the hyperv drivers

Recent kernels support asynchronous probing; most hyperv drivers
can be probed async easily so set the required flag for this.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/hv_balloon.c

@@ -1765,6 +1765,9 @@ static  struct hv_driver balloon_drv = {
 	.id_table = id_table,
 	.probe =  balloon_probe,
 	.remove =  balloon_remove,
+	.driver = {
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
 };
 
 static int __init init_balloon_drv(void)