ACPIPHP: use ACPI dock driver

Modify the acpiphp driver to use the ACPI dock driver for dock
notifications.  Only load the acpiphp driver if we find we have pci dock
devices.

Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>