PNP: convert assign, interface to use pnp_get_resource(), not pnp_resource_table

This removes more direct references to pnp_resource_table from the
pnp_assign_resources() path and the /sys user interface path.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>