PCI: move host bridge-related code to host-bridge.c

Move host bridge-related code from probe.c to a new host-bridge.c.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
index 083a49f..2c224ed 100644
--- a/drivers/pci/Makefile
+++ b/drivers/pci/Makefile
@@ -2,7 +2,7 @@
 # Makefile for the PCI bus specific drivers.
 #
 
-obj-y		+= access.o bus.o probe.o remove.o pci.o \
+obj-y		+= access.o bus.o probe.o host-bridge.o remove.o pci.o \
 			pci-driver.o search.o pci-sysfs.o rom.o setup-res.o \
 			irq.o vpd.o
 obj-$(CONFIG_PROC_FS) += proc.o