drm/nouveau/drm/nouveau: Fix runtime PM leak in nv50_disp_atomic_commit()

A CRTC being enabled doesn't mean it's on! It doesn't even necessarily
mean it's being used. This fixes runtime PM leaks on the P50 I've got
next to me.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/dispnv50/disp.c

@@ -1878,7 +1878,7 @@ nv50_disp_atomic_commit(struct drm_device *dev,
 		nv50_disp_atomic_commit_tail(state);
 
 	drm_for_each_crtc(crtc, dev) {
-		if (crtc->state->enable) {
+		if (crtc->state->active) {
 			if (!drm->have_disp_power_ref) {
 				drm->have_disp_power_ref = true;
 				return 0;