PCI: update pci_create_slot() to take a 'hotplug' param

Slot detection drivers can co-exist with hotplug drivers. The names
of the detected/claimed slots may be different depending on module
load order.

For legacy reasons, we need to allow hotplug drivers to override
the slot name if a detection driver is loaded first (and they find
the same slots).

Creating and overriding slot names should be an atomic operation,
otherwise you get a locking nightmare as various drivers race to
call pci_create_slot().

pci_create_slot() is already serialized by grabbing the pci_bus_sem.

We update the API and add a 'hotplug' param, which is:

	set if the caller is a hotplug driver
	NULL if the caller is a detection driver

pci_create_slot() does not actually use the 'hotplug' parameter in this
patch. A later patch will add the logic that uses it.

Cc: kristen.c.accardi@intel.com
Cc: matthew@wil.cx
Acked-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>