target: Add display pre/post on/off API

Add display pre/post on/off API to support
target specific pre/post on/off sequence.

Change-Id: I125e865db68a8844aa28d910a79890798f119539
diff --git a/target/target_display.c b/target/target_display.c
index 639a83d..0d69434 100644
--- a/target/target_display.c
+++ b/target/target_display.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2012, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
@@ -46,3 +46,19 @@
 {
 	return 0;
 }
+__WEAK int target_display_pre_on()
+{
+	return 0;
+}
+__WEAK int target_display_post_on()
+{
+	return 0;
+}
+__WEAK int target_display_pre_off()
+{
+	return 0;
+}
+__WEAK int target_display_post_off()
+{
+	return 0;
+}