[RFC PATCH v2 0/3] Per SoC descriptor

This patch series introduces a per-soc descriptor which should, in the
end, contain most of the SoC specific operations.

This first patch series introduces the arm_soc_desc structure, adds
per-soc SMP and CPU hotplug operations, and converts both RealView and
VExpress to this new scheme.

Should there be a consensus on these patches, I'll convert all the
other SMP platforms.

Patches against next-20110831. Tested on VExpress (A5 and A15) and
RealView EB-11MP.