drm/nouveau: Use drm_crtc_vblank_off/on

With atomic nv50+ is already converted over to them, but the old
display code is still using it. Found in a 2 year old patch I have
lying around to un-export these old helpers!

v2: Drop the hand-rolled versions from resume/suspend code. Now that
crtc callbacks do this, we don't need a special case for s/r anymore.

v3: Remove unused variables.

v4: Don't remove drm_crtc_vblank_off from suspend paths, non-atomic
nouveau still needs that. But still switch to drm_crtc_vblank_off
since drm_vblank_off will disappear.

Cc: Mario Kleiner <mario.kleiner.de@gmail.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161114114101.21731-1-daniel.vetter@ffwll.ch
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
index 75c90a8d..5698687 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -380,14 +380,14 @@ nouveau_display_fini(struct drm_device *dev, bool suspend)
 	struct nouveau_display *disp = nouveau_display(dev);
 	struct nouveau_drm *drm = nouveau_drm(dev);
 	struct drm_connector *connector;
-	int head;
+	struct drm_crtc *crtc;
 
 	if (!suspend)
 		drm_crtc_force_disable_all(dev);
 
 	/* Make sure that drm and hw vblank irqs get properly disabled. */
-	for (head = 0; head < dev->mode_config.num_crtc; head++)
-		drm_vblank_off(dev, head);
+	drm_for_each_crtc(crtc, dev)
+		drm_crtc_vblank_off(crtc);
 
 	/* disable flip completion events */
 	nvif_notify_put(&drm->flip);
@@ -723,7 +723,7 @@ nouveau_display_resume(struct drm_device *dev, bool runtime)
 	struct nouveau_display *disp = nouveau_display(dev);
 	struct nouveau_drm *drm = nouveau_drm(dev);
 	struct drm_crtc *crtc;
-	int ret, head;
+	int ret;
 
 	if (dev->mode_config.funcs->atomic_commit) {
 		nouveau_display_init(dev);
@@ -777,10 +777,6 @@ nouveau_display_resume(struct drm_device *dev, bool runtime)
 
 	drm_helper_resume_force_mode(dev);
 
-	/* Make sure that drm and hw vblank irqs get resumed if needed. */
-	for (head = 0; head < dev->mode_config.num_crtc; head++)
-		drm_vblank_on(dev, head);
-
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
 		struct nouveau_crtc *nv_crtc = nouveau_crtc(crtc);