libsp: Add high level RXTX buffer handling interface.

This layer provides functions for mapping, unmapping and accessing
FF-A RXTX buffers. It allows other high level interfaces (like memory
management) to use the RXTX buffers internally without the need for
forwarding the RXTX buffer information externally by the user.

Signed-off-by: Imre Kis <imre.kis@arm.com>
Change-Id: I946bcbf818599b2eb12f6ff029f9fc429ccb12b7
4 files changed