platform: msm_shared: defining no-op functions for edp

display.c is shared between platforms. Since LiQUID uses mdp_edp
functions that are defined in mdp5, there is a need to add no-op
functions to mdp4.h and mdp3.
Thus, the compilation for 8960 and 8610 platforms will succeed.

Change-Id: Ib8c37c57d161fe2ba008932c60a54a273332f632
diff --git a/platform/msm_shared/mdp4.c b/platform/msm_shared/mdp4.c
index e347438..b3ade80 100644
--- a/platform/msm_shared/mdp4.c
+++ b/platform/msm_shared/mdp4.c
@@ -408,3 +408,18 @@
 {
 	return mdp_rev;
 }
+
+int mdp_edp_config(struct msm_panel_info *pinfo, struct fbcon_config *fb)
+{
+	return NO_ERROR;
+}
+
+int mdp_edp_on(void)
+{
+	return NO_ERROR;
+}
+
+int mdp_edp_off(void)
+{
+	return NO_ERROR;
+}