The aead files was using a func naming convention which was inconsistent
(ssi vs. cc), included a useless prefix (ssi_aead) and often used
too long function names producing monster func names such as
ssi_aead_gcm_setup_ghash_desc() that made the call site code hard
to read.
Make the code more readable by switching to a simpler, consistent naming
conventionfor all the function defined in the file.