GitLab

Allows to select the chain of trust to use when the Trusted Boot feature
is enabled. This affects both the cert_create tool and the firmware
itself.

Right now, the only available CoT is TBBR.

Change-Id: I7ab54e66508a1416cb3fcd3dfb0f055696763b3d
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>