broadwell: Add small delay before Flex Ratio reboot

In order to prevent possible TPM lockout due to PLTRST assertion
shortly after powering up add a small delay before the reset.
This will affect cold power up only, reboot/resume/warmboot will
all have the flex ratio locked already so this reset is unneeded.

BUG=chrome-os-partner:29859
BRANCH=None
TEST=build and boot on samus.  I tried unsuccessfully to trigger the
TPM lockout, but I was not able to do that consistently without this
patch so it is unknown yet whether this is 100% effective.

Original-Change-Id: Ief8c9261c0268b0f90a3022213ebd2b06633b481
Original-Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/211893
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
(cherry picked from commit 20413f2eafa144f5f381eb6f92d8b959415ca049)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I665e9ed1faa65e88d988660a24bdad40a4c5ab7e
Reviewed-on: http://review.coreboot.org/8957
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>
1 file changed