We only need amd_bus.o for AMD systems with PCI.  arch/x86/pci/Makefile
already depends on CONFIG_PCI=y, so this patch just adds the dependency
on CONFIG_AMD_NB.
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: stable@kernel.org	# 2.6.34+ (needs adjustment for k8 -> amd rename)
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 obj-$(CONFIG_X86_INTEL_MID)    += mrst.o
 
 obj-y                          += common.o early.o
-obj-y                          += amd_bus.o bus_numa.o
+obj-y                          += bus_numa.o
 
+obj-$(CONFIG_AMD_NB)           += amd_bus.o
 obj-$(CONFIG_PCI_CNB20LE_QUIRK)        += broadcom_bus.o
 
 ifeq ($(CONFIG_PCI_DEBUG),y)