Revert "image_signing: skip signing of boot*.efi on reven board".

This reverts commit 4200cb21c7f6c79dacee511400c88994bca5cf7f. The reason
for revert is because this commit fails to load the secure boot.

BUG=b/226099733
TEST=presubmit
RELEASE_NOTE=None

Change-Id: Id25bd22945a177bc3298162160ef610df5f6a478
Reviewed-on: https://cos-review.googlesource.com/c/third_party/platform/vboot_reference/+/31420
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>