Patch merged into coreboot/master: chromeos: vpd: Avoid reading uninitialized VPDs

the following patch was just integrated into master:
commit ffc2260d749a1774a79805ec51bcb67021c07c28
Author: Julius Werner 
Date:   Thu Jan 21 11:12:38 2016 -0800

chromeos: vpd: Avoid reading uninitialized VPDs

This patch adds a check to the VPD parsing code to avoid reading the
    whole thing if the first byte ('type' of the first VPD entry) is 0x00
    or 0xff. These values match the TERMINATOR and IMPLICIT_TERMINATOR types
    which should never occur as the first entry, so this usually means that
    the VPD FMAP section has simply never been initialized correctly. This
    early abort avoids wasting time to read the whole section from SPI flash
    (which we'd otherwise have to since we're not going to find a Google VPD
    2.0 header either).

BRANCH=None
    BUG=None
    TEST=Booted Oak, confirmed that VPD read times dropped from 100ms to
    1.5ms.

Change-Id: I9fc473e06440aef4e1023238fb9e53d45097ee9d
    Signed-off-by: Patrick Georgi 
    Original-Commit-Id: 20a726237e03941ad626a6146700170a45ee7720
    Original-Change-Id: I09bfec3c24d24214fa4e9180878b58d00454f399
    Original-Signed-off-by: Julius Werner 
    Original-Reviewed-on: https://chromium-review.googlesource.com/322897
    Original-Reviewed-by: Hung-Te Lin 
    Reviewed-on: https://review.coreboot.org/13467
    Tested-by: build bot (Jenkins)
    Reviewed-by: Paul Menzel 
    Reviewed-by: Martin Roth

See https://review.coreboot.org/13467 for details.

-gerrit