powerpc/32: Restore previous version of 32-bit PCI code

When I removed the powermac support from arch/ppc/kernel/pci.c,
I overlooked the fact that that file is used in 32-bit ARCH=powerpc
builds.  To prevent problems in future, restore the original version
of that file as arch/powerpc/kernel/pci_32.c, and use that.

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index a94699d..c287980 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -60,7 +60,8 @@
 
 pci64-$(CONFIG_PPC64)		+= pci_64.o pci_dn.o pci_iommu.o \
 				   pci_direct_iommu.o iomap.o
-obj-$(CONFIG_PCI)		+= $(pci64-y)
+pci32-$(CONFIG_PPC32)		:= pci_32.o
+obj-$(CONFIG_PCI)		+= $(pci64-y) $(pci32-y)
 kexec-$(CONFIG_PPC64)		:= machine_kexec_64.o crash.o
 kexec-$(CONFIG_PPC32)		:= machine_kexec_32.o
 obj-$(CONFIG_KEXEC)		+= machine_kexec.o $(kexec-y)