minigbm_helper: close the opened dir

BUG=b:205774533
TEST=no leak

Change-Id: I169dbf05f40f90266620a4b5cf0a8b7bb3c79d9e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/minigbm/+/3282826
Tested-by: Yiwei Zhang <zzyiwei@chromium.org>
Reviewed-by: Chia-I Wu <olv@google.com>
Reviewed-by: Chad Versace <chadversary@chromium.org>
Commit-Queue: Yiwei Zhang <zzyiwei@chromium.org>
1 file changed