image_signing: use GSC nomenclature instead of Cr50

This patch does not yet provide the ability to sign Ti50 images, but
prepares the signing scripts for further modifications to support a
variety of security chip signing flows.

TEST=verified successful signing of a Cr50 image in a test signer
     also created a functional Cr50 image invoking by hand.

Change-Id: Ic103c9fdf7d1c4ea160c7f6849d5ae5a8303c343
Signed-off-by: Vadim Bendebury <>
Tested-by: Vadim Bendebury <>
Reviewed-by: George Engelbrecht <>
Commit-Queue: Vadim Bendebury <>
Auto-Submit: Vadim Bendebury <>
2 files changed