feat(arm): support FW handoff b/w BL1 & BL2

Leverage the framework between BL1 and BL2. Migrate all handoff
structures to the TL.

Change-Id: I79ff3a319596b5656184cde10b5204b10a4d03bb
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
5 files changed