powerpc/p4080: Add support for CPC(Corenet platform cache) on CoreNet platforms

The CoreNet style platforms can have a L3 cache that fronts the memory
controllers.  Enable that cache as well as add information into the
device tree about it.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Dave Liu <daveliu@freescale.com>
Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>