CONFIGS: add new config for CM/DM ECDSA signing in BL2

TC4 uses LMS for BL2 CM/DM signing by default. Increase test coverage by
also testing ECDSA signing.

Change-Id: Ie27cd024f64d7627ec3b95f79f84bf34a9b6745e
Signed-off-by: Amjad Ouled-Ameur <amjad.ouled-ameur@arm.com>
2 files changed