vboot: Add support for OPROM_MATTERS and SLOW_EC

In order to display a "update in progress" screen on devices with
a slow EC or PD chip it may be necessary to also load the VGA
Option ROM when doing EC software sync.

This adds config options for VBOOT_EC_SLOW_UPDATE which simply sets
a flag in the input parameters that is already handled by vboot.

It also adds a config option for VBOOT_OPROM_MATTERS which is a bit
more tricky in that it sets a flag in input parameters, but also
needs to keep track of the option rom being loaded and pass that
flag into VbInit as well.

Since VbInit will clear the NV bit for option rom loaded the check
that is done in vboot_wants_oprom() needs to first compare against
the vboot handoff copy of the input flags.

BUG=chrome-os-partner:32379
BRANCH=samus
TEST=manual testing:
1) in normal mode, with EC/PD in RW, ensure that they are rebooted
to RO and the VGA Option ROM is loaded and the wait screen is
displayed, and then the system is rebooted at the end and the
VGA Option ROM is not loaded.
2) same as #1 with EC/PD in RO already, same result
3) same as #1 with system in developer mode, same result except
there is no reboot at the end of software sync
4) same as #1 with system in developer mode and EC/PD in RO,
ensure that there is no extra reboot at the beginning or end of
software sync.

Original-Change-Id: Ic2b34bf9e7c6cc5498413fa1b8dff6e6207c9d0a
Original-Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/223831
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
(cherry picked from commit 7d7aa89238efb5081885f9386c8e872fc96f573f)

Change-Id: Ib7fb24e6e80e1f7e836bc62246ab9b3e056fd73d
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/8887
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
3 files changed