feat(handoff): port BL31-BL33 interface to fw handoff framework

The firmware handoff framework is a light weight mechanism for sharing
information between bootloader stages. Add support for this framework at
the handoff boundary between runtime firmware BL31 and NS software on FVP.

Change-Id: Ib02e0e4c20a39e32e06da667caf2ce5a28de1e28
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
4 files changed