drm/ttm: Force re-init if ttm_global_init() fails

If we have a failure, decrement the reference count so that the next
call to ttm_global_init() will actually do something instead of assume
everything is all set up.
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Fixes: 62b53b37 ("drm/ttm: use a static ttm_bo_global instance")
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210720181357.2760720-5-jason@jlekstrand.netSigned-off-by: Christian König <christian.koenig@amd.com>

drivers/gpu/drm/ttm/ttm_device.c

@@ -100,6 +100,8 @@ static int ttm_global_init(void)
 	debugfs_create_atomic_t("buffer_objects", 0444, ttm_debugfs_root,
 				&glob->bo_count);
 out:
+	if (ret)
+		--ttm_glob_use_count;
 	mutex_unlock(&ttm_global_mutex);
 	return ret;
 }