xen: Add initialisation of Xen

The xenpv machine use the common init function.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/hw/xen_machine_pv.c b/hw/xen_machine_pv.c
index 0d7f73e..7985d11 100644
--- a/hw/xen_machine_pv.c
+++ b/hw/xen_machine_pv.c
@@ -113,6 +113,7 @@
     .desc = "Xen Para-virtualized PC",
     .init = xen_init_pv,
     .max_cpus = 1,
+    .default_machine_opts = "accel=xen",
 };
 
 static void xenpv_machine_init(void)