plat/arm: Introduce TC0 platform ...

This patch adds support for Total Compute (TC0) platform. It is an
initial port and additional features are expected to be added later.

TC0 has a SCP which brings the primary Cortex-A out of reset
which starts executing BL1. TF-A optionally authenticates the SCP
ram-fw available in FIP and makes it available for SCP to copy.

Some of the major features included and tested in this platform
port include TBBR, PSCI, MHUv2 and DVFS.

Change-Id: I1675e9d200ca7687c215009eef483d9b3ee764ef
Signed-off-by: Usama Arif <usama.arif@arm.com>