PCI hotplug: Change link order of pciehp & acpiphp

Some hardware exposes PCIE slots in such a way that they can be claimed
by either the acpiphp or pciehp driver. pciehp is the preferred driver
if the firmware allows the OS to claim control via the _OSC method so
should be loaded first - if it fails to bind (either due to a missing
_OSC method or the firmware refusing to hand off control) then we can
fall back to acpiphp or a vendor-specific driver.

This patch simply changes the link order to ensure that pciehp will be
initialised before acpiphp if both are statically built into the kernel.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>