drm/nouveau: fix reference count leak in nv50_disp_atomic_commit

nv50_disp_atomic_commit() calls calls pm_runtime_get_sync and in turn
increments the reference count. In case of failure, decrement the
ref count before returning the error.
Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

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

@@ -2171,8 +2171,10 @@ nv50_disp_atomic_commit(struct drm_device *dev,
 	int ret, i;
 
 	ret = pm_runtime_get_sync(dev->dev);
-	if (ret < 0 && ret != -EACCES)
+	if (ret < 0 && ret != -EACCES) {
+		pm_runtime_put_autosuspend(dev->dev);
 		return ret;
+	}
 
 	ret = drm_atomic_helper_setup_commit(state, nonblock);
 	if (ret)