vboot: remove secdata TPM backend code

In vboot 2 design, secdata spaces are read/written by the vboot
caller, and not by vboot itself.  We still need to maintain a
vb2ex_commit_data callback for edge cases, such as when the vboot
UI prompts the user to reboot.

BUG=b:124141368, chromium:972956
TEST=Build locally, flash and boot eve,
     check logs for secdata writes and locks
TEST=make clean && make runtests

Change-Id: Ib3b628549185749a290dd65e297f2e19adecbc66
Cq-Depend: chromium:1958012
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1958070
Reviewed-by: Joel Kitching <kitching@chromium.org>
Commit-Queue: Joel Kitching <kitching@chromium.org>
Tested-by: Joel Kitching <kitching@chromium.org>
23 files changed