vboot: Introduce kconfig variable for VBNV backing storage

This introduces a new kconfig variable to select the VBNV backing
store explicitly instead of inferring it from CPU/SoC architecture.

x86 platforms have historically relied only on CMOS to store VBNV
variables, while ARM-based platforms have traditionally relied on
the EC. Neither of those solutions are going to scale well into
the future if/when CMOS disappears and we make ARM-based systems
without an EC.

BUG=chrome-os-partner:29546
BRANCH=none
TEST=compiled for nyan_blaze and samus

Original-Signed-off-by: David Hendricks <dhendrix@chromium.org>
Original-Change-Id: I4a8dadfb6bb666baf1ed4bec98b29c145dc4a1e7
Original-Reviewed-on: https://chromium-review.googlesource.com/213877
Original-Reviewed-by: Stefan Reinauer <reinauer@google.com>
Original-Commit-Queue: Vadim Bendebury <vbendeb@chromium.org>
Original-Tested-by: Vadim Bendebury <vbendeb@chromium.org>
(cherry picked from commit d088fc71b2e2b45e826d3dedb8e536ad58b8d296)

Change-Id: Iea325a8c4d07055143e993d89b827f86b8312330
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/8777
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

0 files changed, 0 insertions, 0 deletions