scripts/image_signing/swap_ecrw: Support ecrw.version

Add "ecrw.version" to FW_MAIN_A and FW_MAIN_B to allow easier tracking
of the "ecrw" version in an AP firmwar image. Even if "ecrw.version"
doesn't exist in the original AP image, the CBFS file will still be
added.

BUG=b:325886850
TEST=make runtestscripts
BRANCH=none

Cq-Depend: chromium:5492530
Disallow-Recycled-Builds: all
Change-Id: Id2846fab6abedd039b6a7555b0c1de3a7674542b
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/5492688
Reviewed-by: Julius Werner <jwerner@chromium.org>
Commit-Queue: Julius Werner <jwerner@chromium.org>
5 files changed