PCI: Expose pci_load_saved_state for public consumption.

We have the pci_load_and_free_saved_state, and pci_store_saved_state
but are missing the functionality to just load the state
multiple times in the PCI device without having to free/save
the state.

This patch makes it possible to use this function.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>