vboot: relocate private RSA function headers

Previously, functions that need to be tested but not exposed
to vboot API were placed in vboot_test.h.  Now, the approach
of placing them in a xyz_private.h header file is preferred.

BUG=b:124141368, chromium:968464
TEST=make clean && make runtests

Signed-off-by: Joel Kitching <kitching@google.com>
Change-Id: I8be50d95c533b277b509aabb503ae05f69662a33
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2641344
Tested-by: Joel Kitching <kitching@chromium.org>
Commit-Queue: Joel Kitching <kitching@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@chromium.org>
4 files changed