ACPI: create notifier chain to get hotkey events to graphics driver

Kernel mode graphics drivers need this ACPI notifier chaine
so that they can get notified upon hotkey events.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index fb7171b..3f9f141 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -321,6 +321,9 @@
 
 extern struct kobject *acpi_kobj;
 extern int acpi_bus_generate_netlink_event(const char*, const char*, u8, int);
+extern int acpi_notifier_call_chain(struct acpi_device *, u32, u32);
+extern int register_acpi_notifier(struct notifier_block *);
+extern int unregister_acpi_notifier(struct notifier_block *);
 /*
  * External Functions
  */