xen/arm: initialize pm functions later

If we are running in dom0, we have to wait for the arch specific code to
complete the initialization in order for us to successfully reset the
power_off and pm_restart functions.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>

arch/arm/xen/enlighten.c

@@ -272,12 +272,18 @@ static int __init xen_guest_init(void)
 	if (!xen_initial_domain())
 		xenbus_probe(NULL);
 
+	return 0;
+}
+core_initcall(xen_guest_init);
+
+static int __init xen_pm_init(void)
+{
 	pm_power_off = xen_power_off;
 	arm_pm_restart = xen_restart;
 
 	return 0;
 }
-core_initcall(xen_guest_init);
+subsys_initcall(xen_pm_init);
 
 static irqreturn_t xen_arm_callback(int irq, void *arg)
 {