firmware: Remove LoadKernelParams from APIs

This cleans up the vboot functions which handle display so they don't
need to pass it around.  Eventually, it'll be absorbed by vb2_context.

BUG=chromium:611535
BRANCH=none
TEST=make runtests; build_packages --board=reef chromeos-firmware; boot reef

Change-Id: I58169dfd37abe657f9b9aa339cc72ffa398329e0
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/414288
Reviewed-by: Shelley Chen <shchen@chromium.org>
13 files changed