vboot2: Change preamble to contain a list of signatures

Use struct vb2_signature2 objects to hold the hashes of firmware
components, rather than a separate vb2_fw_preamble2_hash struct.
Better for code reuse.

BUG=chromium:423882
BRANCH=none
TEST=VBOOT2=1 make runtests

Change-Id: Ia9e23c1488a884f2d6fab4c4be51b25d3ff25c2f
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/228241
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
6 files changed