CR50: introduce a fixed endorsement seed & certs
CR50: introduce a fixed endorsement seed & certs

This change introduces a 'fixed' endorsement seed,
and corresponding certificates.  This fixed seed
is used in the endorsement process when a production
mode chip is running dev-signed firmware (or vice-versa).

The fixed certificates are untrusted by production
services, and are suitable for use in a development
environment.

BRANCH=none
BUG=none
TEST=build succeeds

Change-Id: Ifad0b361413a10f88c4977b03033a30a750cd536
Signed-off-by: nagendra modadugu <5dc366ddbf8fb5981f46478e8436ef712a08b71b@google.com>
Reviewed-on: https://chromium-review.googlesource.com/401634
Commit-Ready: Nagendra Modadugu <5dc366ddbf8fb5981f46478e8436ef712a08b71b@google.com>
Tested-by: Nagendra Modadugu <5dc366ddbf8fb5981f46478e8436ef712a08b71b@google.com>
Reviewed-by: Bill Richardson <129945214b1d548d8e49b6c29c43094f8c78057f@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec