feat(ff-a): change manifest messaging method

Align documentation with changes of messaging method for partition
manifest:
      - Bit[0]: support for receiving direct message requests
      - Bit[1]: support for sending direct messages
      - Bit[2]: support for indirect messaging
      - Bit[3]: support for managed exit
Change the optee_sp_manifest to align with the new messaging method
description.

Signed-off-by: Maksims Svecovs <maksims.svecovs@arm.com>
Change-Id: I333e82c546c03698c95f0c77293018f8dca5ba9c
2 files changed