drm/exynos: add plane enable/disable

The plane enable/disable can control only a power of plane, so they will
be helpful to handle planes with dpms.

Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@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 1bd681c..1c90a9a 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.h
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.h
@@ -59,12 +59,14 @@
  *
  * @mode_set: copy drm overlay info to hw specific overlay info.
  * @commit: apply hardware specific overlay data to registers.
+ * @enable: enable hardware specific overlay.
  * @disable: disable hardware specific overlay.
  */
 struct exynos_drm_overlay_ops {
 	void (*mode_set)(struct device *subdrv_dev,
 			 struct exynos_drm_overlay *overlay);
 	void (*commit)(struct device *subdrv_dev, int zpos);
+	void (*enable)(struct device *subdrv_dev, int zpos);
 	void (*disable)(struct device *subdrv_dev, int zpos);
 };