drm/exynos: make wait_for_vblank a manager op

Changelog v2:
remove unnecessay wait_for_vblank call.
- with this patch, wait_for_vblank callback is moved from
  overlay ops to manager ops so it should be removed and
  it doesn't need to wait vblank signal at plane disable.

Changelog v1:
The wait_for_vblank callback is moved from overlay ops to manager ops
of exynos drm driver. Also, the check for DPMS OFF of encoder is
removed before calling wait_for_vblank.

Signed-off-by: Prathyush K <prathyush.k@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.h b/drivers/gpu/drm/exynos/exynos_drm_drv.h
index a4702a8..5a8c1f2 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.h
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.h
@@ -74,8 +74,6 @@
  * @commit: apply hardware specific overlay data to registers.
  * @enable: enable hardware specific overlay.
  * @disable: disable hardware specific overlay.
- * @wait_for_vblank: wait for vblank interrupt to make sure that
- *	hardware overlay is disabled.
  */
 struct exynos_drm_overlay_ops {
 	void (*mode_set)(struct device *subdrv_dev,
@@ -83,7 +81,6 @@
 	void (*commit)(struct device *subdrv_dev, int zpos);
 	void (*enable)(struct device *subdrv_dev, int zpos);
 	void (*disable)(struct device *subdrv_dev, int zpos);
-	void (*wait_for_vblank)(struct device *subdrv_dev);
 };
 
 /*
@@ -186,6 +183,8 @@
  * @commit: set current hw specific display mode to hw.
  * @enable_vblank: specific driver callback for enabling vblank interrupt.
  * @disable_vblank: specific driver callback for disabling vblank interrupt.
+ * @wait_for_vblank: wait for vblank interrupt to make sure that
+ *	hardware overlay is updated.
  */
 struct exynos_drm_manager_ops {
 	void (*dpms)(struct device *subdrv_dev, int mode);
@@ -200,6 +199,7 @@
 	void (*commit)(struct device *subdrv_dev);
 	int (*enable_vblank)(struct device *subdrv_dev);
 	void (*disable_vblank)(struct device *subdrv_dev);
+	void (*wait_for_vblank)(struct device *subdrv_dev);
 };
 
 /*