This patch adds a tool that generates all the necessary elements
to establish the chain of trust (CoT) between the images.
The tool reads the binary images and signing keys and outputs the
corresponding certificates that will be used by the target at run
time to verify the authenticity of the images.
Note: the platform port must provide the file platform_oid.h. This
file will define the OIDs of the x509 extensions that will be added
to the certificates in order to establish the CoT.
Change-Id: I2734d6808b964a2107ab3a4805110698066a04be
6f97162237