drm/exynos: fix overlay updating issue

Chagelog v2:
Move encoder's dpms updating into exynos_drm_encoder_commit
function because when crtc's dpms is updated, encoder's dpms
is updated also. This would induce the issue that encoder
isn't disabled after crtc is disabled.

Changelog v1:
This patch fixes a issue that overlay data aren't applied
to real hardware when dpms off goes to on after setcrtc
was requested like below,
    dpms off -> setcrtc -> dpms off -> dpms on

For this, it makes encoder's dpms to be updated when
setcrtc is requested.
Signed-off-by: NInki Dae <inki.dae@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_encoder.c

@@ -226,6 +226,12 @@ static void exynos_drm_encoder_commit(struct drm_encoder *encoder)
 	 * already updated or not by exynos_drm_encoder_dpms function.
 	 */
 	exynos_encoder->updated = true;
+
+	/*
+	 * In case of setcrtc, there is no way to update encoder's dpms
+	 * so update it here.
+	 */
+	exynos_encoder->dpms = DRM_MODE_DPMS_ON;
 }
 
 static void exynos_drm_encoder_disable(struct drm_encoder *encoder)