arm64: dts: fast models: Add DTS fo Base RevC FVP

Fixed Virtual Platforms(FVP) Base RevC model is an emulated Arm platform
with GICv3, PCIe, SMMUv3 and various other features. These are available
free of charge on the Arm Community website at Arm Development
Platforms[1].

It resembles the Foundation Platform, which is a simple FVP that
includes an Armv8‑A AEM processor model but this has two cluster of four
cores, a CCI-550 interconnect, an SMMU and two PCI devices.

In order to enable development of software, let's add a description of
the Revison C version of Base platform.

The documentation for this FVP model is available @[2] for reference.

[1] https://community.arm.com/dev-platforms/
[2] https://static.docs.arm.com/100966/1104/fast_models_fvp_rg_100966_1104_00_en.pdf

Cc: Vincent Stehlé <vincent.stehle@arm.com>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
[sudeep.holla: aligned interrupt-map with other DTS, added SPE, changed
 PMU to use GIC PPI, moved to PSCI v0.2, commit log rewording]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>