commander: fix emergency power off

From what I can see the CONFIG_BOARDCTL_POWEROFF is not really used
anywhere, however, the BOARD_HAS_POWER_CONTROL is something that is set,
e.g. for the Mantis, to allow power off.

src/modules/commander/Commander.cpp

@@ -3734,7 +3734,7 @@ void Commander::battery_status_check()
 	if (update_internal_battery_state) {
 
 		if (_battery_warning == battery_status_s::BATTERY_WARNING_EMERGENCY) {
-#if defined(CONFIG_BOARDCTL_POWEROFF)
+#if defined(BOARD_HAS_POWER_CONTROL)
 
 			if (shutdown_if_allowed() && (px4_shutdown_request(400_ms) == 0)) {
 				mavlink_log_critical(&_mavlink_log_pub, "Dangerously low battery! Shutting system down\t");
@@ -3752,7 +3752,7 @@ void Commander::battery_status_check()
 					     "Dangerously low battery! System shut down failed");
 			}
 
-#endif // CONFIG_BOARDCTL_POWEROFF
+#endif // BOARD_HAS_POWER_CONTROL
 		}
 	}
 }