trousers: Add secure UnloadBlob functions

The TpmManagerService fuzzer need these function, otherwise it will
crash on fuzzed inputs.

BUG=b:195262420
TEST=tast run hwsec.* on relm

Change-Id: Id13ff3bf46d68658fe9daea645c31ec043ee5cd6
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/trousers/+/3102472
Tested-by: Domen Su <domen@google.com>
Commit-Queue: John L Chen <zuan@chromium.org>
Reviewed-by: John L Chen <zuan@chromium.org>
Reviewed-by: Andrey Pronin <apronin@chromium.org>
2 files changed