tools: Add firmware authenticated encryption tool

Add firmware authenticated encryption tool which utilizes OpenSSL
library to encrypt firmwares using a key provided via cmdline. Currently
this tool supports AES-GCM as an authenticated encryption algorithm.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Change-Id: I60e296af1b98f1912a19d5f91066be7ea85836e4
8 files changed