Put a "normal" kernel signed with "normal" keys in slot "B".

This kernel can be installed to the disk without any special processing which
helps make the vblock in the stateful partition unnecessary.

BUG=chromium:398236
TEST=Ran a tryjob for butterfly with --hwtest.

Change-Id: I0fca396a7ff7174f9e3c7be2fc59ded02161c4a4
Reviewed-on: https://chromium-review.googlesource.com/210616
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>
3 files changed