parisc: Directly call machine_power_off() in power button driver

Signed-off-by: Helge Deller <[e-mail]>
Tested-by: Matt Turner <[e-mail]>

drivers/parisc/power.c

···
 		/* send kill signal */
 		if (kill_cad_pid(SIGINT, 1)) {
 			/* just in case killing init process failed */
-			if (pm_power_off)
-				pm_power_off();
+			machine_power_off();
 		}
 	}
 }