Merge changes from topic "tbbr/fw_enc" into integration

* changes:
  docs: qemu: Add instructions to boot using FIP image
  docs: Update docs with firmware encryption feature
  qemu: Support optional encryption of BL31 and BL32 images
  qemu: Update flash address map to keep FIP in secure FLASH0
  Makefile: Add support to optionally encrypt BL31 and BL32
  tools: Add firmware authenticated encryption tool
  TBB: Add an IO abstraction layer to load encrypted firmwares
  drivers: crypto: Add authenticated decryption framework