msm_fb: display: Wait for external vsync before DTV IOMMU unmap

In play wait call for DTV, software waits for overlay1 done before
unmapping IOMMU buffers. This is replaced by external vsync wait
to avoid page faults.

Change-Id: I67d3615121e9eda3a4378553049a41e32860a520
Signed-off-by: Ravishangar Kalyanam <rkalya@codeaurora.org>
diff --git a/drivers/video/msm/mdp4_overlay.c b/drivers/video/msm/mdp4_overlay.c
index c58fe76..6d4e44b 100644
--- a/drivers/video/msm/mdp4_overlay.c
+++ b/drivers/video/msm/mdp4_overlay.c
@@ -2727,7 +2727,7 @@
 	if (mfd->use_ov1_blt)
 		mdp4_overlay1_update_blt_mode(mfd);
 
-	mdp4_overlay_dtv_wait_for_ov(mfd, pipe);
+	mdp4_overlay_dtv_wait4vsync();
 	mdp4_iommu_unmap(pipe);
 
 	mutex_unlock(&mfd->dma->ov_mutex);