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>
diff --git a/drivers/xen/xen-acpi-cpuhotplug.c b/drivers/xen/xen-acpi-cpuhotplug.c
index 80875fb..3e62ee4 100644
--- a/drivers/xen/xen-acpi-cpuhotplug.c
+++ b/drivers/xen/xen-acpi-cpuhotplug.c
@@ -313,7 +313,7 @@
 		goto out;
 	}
 
-	(void) acpi_evaluate_hotplug_ost(handle, event, ost_code, NULL);
+	(void) acpi_evaluate_ost(handle, event, ost_code, NULL);
 
 out:
 	acpi_scan_lock_release();