cros_bundle_firmware: zero out unused space in RW sections pre-signing

This mirrors the current behavior for the cb_with_fmap file, leading to
identical content.

BUG=chromium:595715
BRANCH=none
TEST=verify bit-equivalence of regions between image.bin and cb_with_fmap
with CL:397219 or similar.

Change-Id: Ied435269247efa8303d76e1b8e2dd0b2a1f7f25a
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://chromium-review.googlesource.com/397622
Commit-Ready: Patrick Georgi <pgeorgi@chromium.org>
Tested-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-by: Patrick Georgi <pgeorgi@chromium.org>
1 file changed