feat(tc): port BL2-BL31 interface to firmware handoff framework

Adding support for this framework at the handoff boundary between
firmware stage BL2 and BL31 on TC.

Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: I8e29b859e57a732e53f7532a5869ed4c8665b161
2 files changed