xen: When calling power_off, don't call the halt function.

.. As it won't actually power off the machine.
Reported-by: Sven Köhler <sven.koehler@gmail.com>
Tested-by: Sven Köhler <sven.koehler@gmail.com>
Signed-off-by: Tom Goetz <tom.goetz@virtualcomputer.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/xen/enlighten.c

@@ -1033,6 +1033,13 @@ static void xen_machine_halt(void)
 	xen_reboot(SHUTDOWN_poweroff);
 }
 
+static void xen_machine_power_off(void)
+{
+	if (pm_power_off)
+		pm_power_off();
+	xen_reboot(SHUTDOWN_poweroff);
+}
+
 static void xen_crash_shutdown(struct pt_regs *regs)
 {
 	xen_reboot(SHUTDOWN_crash);
@@ -1058,7 +1065,7 @@ int xen_panic_handler_init(void)
 static const struct machine_ops xen_machine_ops __initconst = {
 	.restart = xen_restart,
 	.halt = xen_machine_halt,
-	.power_off = xen_machine_halt,
+	.power_off = xen_machine_power_off,
 	.shutdown = xen_machine_halt,
 	.crash_shutdown = xen_crash_shutdown,
 	.emergency_restart = xen_emergency_restart,