vboot: create secdata_kernel flag to disable diagnostic UI

Diagnostic UI is currently not ready to ship. Disable
the UI (including both entry point and the UI itself)
until it is ready.

Also remove unused mock_presence from vboot_api_kernel4_tests.

BUG=b:155848434, b:162486211
TEST=make clean && make runtests

Signed-off-by: Joel Kitching <kitching@google.com>
Change-Id: I5cad7d40b2f52015f17f930a4d061c9cdf976a49
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2328985
Tested-by: Chun-ta Lin <itspeter@chromium.org>
Commit-Queue: Chun-ta Lin <itspeter@chromium.org>
Reviewed-by: Joel Kitching <kitching@chromium.org>
8 files changed