ACPI: Drop acpi_evaluate_hotplug_ost() and ACPI_HOTPLUG_OST

Replace acpi_evaluate_hotplug_ost() with acpi_evaluate_ost()
everywhere and drop the ACPI_HOTPLUG_OST symbol so that hotplug
_OST is supported unconditionally.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>

drivers/xen/xen-acpi-memhotplug.c

@@ -285,7 +285,7 @@ static void acpi_memory_device_notify(acpi_handle handle, u32 event, void *data)
 		return;
 	}
 
-	(void) acpi_evaluate_hotplug_ost(handle, event, ost_code, NULL);
+	(void) acpi_evaluate_ost(handle, event, ost_code, NULL);
 	return;
 }