arm-bsp/linux: add ffa driver to TC0

This patch contains initial version of ffa driver adopted for
android11-5.4-lts kernel.

This is based on prototype ffa driver released by Arm.

Signed-off-by: Arunachalam Ganapathy <arunachalam.ganapathy@arm.com>
Change-Id: Idb198cc77368a95257f1b5bff37b17bd13144109
Signed-off-by: Jon Mason <jon.mason@arm.com>