ACPI processor: Use safe_halt() rather than halt() in acpi_idle_play_dead()

ACPI code is shared by arch/x86 and arch/ia64. ia64 doesn't provide a plain
"halt()" function.  Use safe_halt() instead.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Tested-by: Boris Ostrovsky <boris.ostrovsky@amd.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/processor_idle.c

@@ -786,7 +786,7 @@ static int acpi_idle_play_dead(struct cpuidle_device *dev, int index)
 	while (1) {
 
 		if (cx->entry_method == ACPI_CSTATE_HALT)
-			halt();
+			safe_halt();
 		else if (cx->entry_method == ACPI_CSTATE_SYSTEMIO) {
 			inb(cx->address);
 			/* See comment in acpi_idle_do_entry() */