plat/arm/sgi: Add board support for SGI-Clark.Helios platform

SGI-Clark.Helios platform is similar to SGI-Clark.Ares platform.
The difference between these two platforms is the CPU type and
the number of CPUs. Add the base support for SGI-Clark.Helios platform.

Change-Id: I2b04cb3fb953907848b4fab016e3648899ca4256
Signed-off-by: Chandni Cherukuri <chandni.cherukuri@arm.com>
6 files changed