certify_bootimg: support gki-info.txt am: 67def5e80a am: a4bc64e48e am: 4cb8e5e915

Original change: https://android-review.googlesource.com/c/platform/system/tools/mkbootimg/+/2033163

Change-Id: Iace8882dddaf2604e3bfa030ee2b638e0c38a15e