drm/exynos: fixed page flip issue.

with vblank_refcount = 1, there was the case that drm_vblank_put
is called by specific page flip function so this patch fixes the
issue.

Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
index e3861ac..de81883 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
@@ -307,9 +307,6 @@
 		 */
 		event->pipe = exynos_crtc->pipe;
 
-		list_add_tail(&event->base.link,
-				&dev_priv->pageflip_event_list);
-
 		ret = drm_vblank_get(dev, exynos_crtc->pipe);
 		if (ret) {
 			DRM_DEBUG("failed to acquire vblank counter\n");
@@ -318,6 +315,9 @@
 			goto out;
 		}
 
+		list_add_tail(&event->base.link,
+				&dev_priv->pageflip_event_list);
+
 		crtc->fb = fb;
 		ret = exynos_drm_crtc_update(crtc);
 		if (ret) {