cros_bundle_firmware: Pack SeaBIOS into rw-legacy section
cros_bundle_firmware: Pack SeaBIOS into rw-legacy section

Instead of making SeaBIOS the coreboot payload, we need to
pack it into the rw-legacy section of the fmap, so it can
be started by pressing CTRL-L at the dev mode screen.

CQ-DEPEND=CL:35130 CL:35131 CL:35134 CL:35135

BUG=chrome-os-partner:6108
TEST=emerge-link chromeos-bootimage, see SeaBIOS CBFS is
     packed into the rw-legacy section
BRANCH=link

Change-Id: I8a14cac854318c83d770f49eb9fb2ca226a6e8aa
Reviewed-on: https://gerrit.chromium.org/gerrit/35136
Commit-Ready: Stefan Reinauer <0ab4fef0c228799b0c44e01c732054569b690b58@chromium.org>
Reviewed-by: Stefan Reinauer <0ab4fef0c228799b0c44e01c732054569b690b58@chromium.org>
Tested-by: Stefan Reinauer <0ab4fef0c228799b0c44e01c732054569b690b58@chromium.org>

marineam/coreos-dev-util,marineam/coreos-dev-util,mgireesh05/dev-util,mgireesh05/dev-util,mgireesh05/dev-util,coreos/dev-util,coreos/dev-util,coreos/dev-util