HOW.optimus: Re-enable signing of unlocked Barebox images for SpaceCast

The manufacturing team encountered that adapting their procedures to a
locked Barebox would involve significantly more work than initially
expected. Therefore SpaceCast development builds will be distributed
with signed unlocked Barebox images. To protect user data the PCR
registers of the TPM are extended with different values in the locked
and the unlocked case.

Change-Id: I1c12dbfb069686357212896391adfd07dabd6893
1 file changed