4xx PLB to PCI-X support

This adds base support code for the 4xx PCI-X bridge. It also provides placeholders for the PCI and PCI-E version but they aren't supported with this patch.

The bridges are configured based on device-tree properties.

---

Tested on 440GP only so far.

 arch/powerpc/sysdev/Makefile     |    3 
 arch/powerpc/sysdev/ppc4xx_pci.c |  339 +++++++++++++++++++++++++++++++++++++++
 arch/powerpc/sysdev/ppc4xx_pci.h |  106 ++++++++++++
 3 files changed, 448 insertions(+)

@@ -27,6 +27,9 @@ obj-$(CONFIG_PPC_I8259)		+= i8259.o
 obj-$(CONFIG_PPC_83xx)		+= ipic.o
 obj-$(CONFIG_4xx)		+= uic.o
 obj-$(CONFIG_XILINX_VIRTEX)	+= xilinx_intc.o
+ifeq ($(CONFIG_PCI),y)
+obj-$(CONFIG_4xx)		+= ppc4xx_pci.o
+endif
 endif
 
 # Temporary hack until we have migrated to asm-powerpc