openrisc: Use do_kernel_power_off()

After commit 14c56787 ("power: reset: syscon-poweroff: Use
devm_register_sys_off_handler(POWER_OFF)") setting up of pm_power_off
was removed from the driver, this causes OpenRISC platforms using
syscon-poweroff to no longer shutdown.

The kernel now supports chained power-off handlers. Use
do_kernel_power_off() that invokes chained power-off handlers.  All
architectures have moved away from using pm_power_off except OpenRISC.

This patch migrates openrisc to use do_kernel_power_off() instead of the
legacy pm_power_off().

Fixes: 14c56787 ("power: reset: syscon-poweroff: Use devm_register_sys_off_handler(POWER_OFF)")
Signed-off-by: Stafford Horne <shorne@gmail.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>

arch/openrisc/kernel/process.c

@@ -65,7 +65,7 @@ void machine_restart(char *cmd)
 }
 
 /*
- * This is used if pm_power_off has not been set by a power management
+ * This is used if a sys-off handler was not set by a power management
  * driver, in this case we can assume we are on a simulator.  On
  * OpenRISC simulators l.nop 1 will trigger the simulator exit.
  */
@@ -89,10 +89,8 @@ void machine_halt(void)
 void machine_power_off(void)
 {
 	printk(KERN_INFO "*** MACHINE POWER OFF ***\n");
-	if (pm_power_off != NULL)
-		pm_power_off();
-	else
-		default_power_off();
+	do_kernel_power_off();
+	default_power_off();
 }
 
 /*