PNP: make interfaces private to the PNP core

The interfaces for registering protocols, devices, cards,
and resource options should only be used inside the PNP core.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Acked-By: Rene Herman <rene.herman@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>