[POWERPC] 4xx: Base support for 440SPe "Katmai" eval board

This adds base support for the Katmai board, including PCI-X and
PCI-Express (but no RTC, nvram, etc... yet).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Stefan Roese <sr@denx.de>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>