Vulkan: Fix re-creating buffer storage. BUG=angleproject:2200 Change-Id: Id60e857517cce9c0bfa272e4e6a399f236e395f7 Reviewed-on: https://chromium-review.googlesource.com/741548 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>