PCI: Move pci_hp_add_bridge() to drivers/pci/probe.c

There is not much point of having a file with a single function in it.
Instead we can just move pci_hp_add_bridge() to drivers/pci/probe.c and
make it available always when PCI core is enabled.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[bhelgaas: convert printk to dev_err()]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>