Moving the context pointers for each CPU into the per-cpu data
allows for much more efficient access to the contexts for the
current CPU.
Change-Id: Id784e210d63cbdcddb44ac1591617ce668dbc29f
This patch prepares the per-cpu pointer cache for wider use by:
* renaming the structure to cpu_data and placing in new header
* providing accessors for this CPU, or other CPUs
* splitting the initialization of the TPIDR pointer from the
initialization of the cpu_data content
* moving the crash stack initialization to a crash stack function
* setting the TPIDR pointer very early during boot
Change-Id: Icef9004ff88f8eb241d48c14be3158087d7e49a3