cosmos: add template files for libpayload

this adds template files to build chromeos-bootimage. it also adjusts
coreboot.rom size and flash map offset with respect to the board's fmap.dts.

BUG=chrome-os-partner:32772
BRANCH=none
TEST=Built chromeos-bootimage
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>

Change-Id: I97f2ac8ffc7232c7a6c6d40deb8a35630d3d62a7
Reviewed-on: https://chromium-review.googlesource.com/222662
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
Commit-Queue: Daisuke Nojiri <dnojiri@chromium.org>
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
6 files changed