Merge changes from topic "hm/handoff" into integration

* changes:
  feat(handoff): add support for RESET_TO_BL2
  feat(arm): support FW handoff b/w BL1 & BL2
  feat(handoff): add TL source files to BL1
  feat(handoff): add TE's for BL1 handoff interface
  refactor(bl1): clean up bl2 layout calculation
  feat(arm): support FW handoff b/w BL2 & BL31