vboot2: implement select_firmware for pre-romstage verification

This patch has a basic structure of vboot2 integration. It supports only Nyans,
which have bootblock architecture and romstage architecture are
compatible from linker's perspective.

TEST=Built with VBOOT2_VERIFY_FIRMWARE on/off. Booted Nyan Blaze.
BUG=None
BRANCH=none
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>

Original-Change-Id: I4bbd4d0452604943b376bef20ea8a258820810aa
Original-Reviewed-on: https://chromium-review.googlesource.com/204522
Original-Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
Original-Commit-Queue: Daisuke Nojiri <dnojiri@chromium.org>
Original-Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
(cherry picked from commit a6bce0cbed34def60386f3d9aece59e739740c58)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I63ddfbf463c8a83120828ec8ab994f8146f90001
Reviewed-on: http://review.coreboot.org/8160
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins)
16 files changed