target: Add SPI display post on API

Add display post on API to support target specific post on sequence.

Change-Id: Ie114fbe6bf9ca9fb291199e41733a6dc0839e597
Signed-off-by: Wenjun Zhang <wjzhan@codeaurora.org>
diff --git a/target/target_display.c b/target/target_display.c
index d32e90d..ff0bff8 100644
--- a/target/target_display.c
+++ b/target/target_display.c
@@ -146,3 +146,8 @@
 {
 	return 0;
 }
+
+__WEAK int mdss_spi_cmd_post_on(struct msm_panel_info *pinfo)
+{
+	return 0;
+}