[coreboot-gerrit] Patch merged into coreboot/master: chromeos: Add vbnv wrapper for the different backends

the following patch was just integrated into master:
commit 88b28ada69d032faf37753f0595658d507859d4a
Author: Duncan Laurie 
Date:   Mon Jan 25 17:13:27 2016 -0800

chromeos: Add vbnv wrapper for the different backends

Add a wrapper around the vbnv implementations and call into the different
    backend functions from there.  Also move some of the common functions to
    the common code and simplify the backend drivers.  This will allow some
    of the code to be re-used so the CMOS backend can backup the data into
    the flash backend.

One side effect of this is that the cache of VBNV was removed from CMOS
    and EC backends and moved into the VBNV wrapper, but the flash backend
    also still has a separate cache because it has more state and complexity
    in the implementation.  The wrapper cached data is not used for normal
    vbnv_read/vbnv_write because some callers need the ability to force a
    write if the backend storage is cleared (i.e. CMOS clear).

BUG=chrome-os-partner:47915
    BRANCH=glados
    TEST=build and boot on chell

Change-Id: I4d2e0e99af7e8a44aec77ad9991507401babcca6
    Signed-off-by: Patrick Georgi 
    Original-Commit-Id: c30f60434a64f6c0eb9ede45d48ddafff19dd24f
    Original-Change-Id: Ia97f6607c5ad837b9aa10b45211137221ccb93a0
    Original-Signed-off-by: Duncan Laurie 
    Original-Reviewed-on: https://chromium-review.googlesource.com/324120
    Original-Reviewed-by: Aaron Durbin 
    Reviewed-on: https://review.coreboot.org/13597
    Tested-by: build bot (Jenkins)
    Reviewed-by: Martin Roth

See https://review.coreboot.org/13597 for details.

-gerrit