This changeset moves all "system library" code to this directory.
System library code includes all common libraries
of routines (PIC, system controller, host bridge, kernel feature
enablement are all examples of things that belong here). The existing
arch/ppc/kernel/ directory keeps all "core" CPU support.  Cache
handling, basic cpu startup, tlb manipulation, and core kernel
code all belong here.  The arch/ppc/platforms/ directory now
contains only platform family specific files.  For SoC processors
this includes the OCP glue-code that defines an SoC family.