vfio/pci: Fix unchecked return value

There's nothing we can do different if pci_load_and_free_saved_state()
fails, other than maybe print some log message, but the actual re-load
of the state is an unnecessary step here since we've only just saved
it.  We can cleanup a coverity warning and eliminate the unnecessary
step by freeing the state ourselves.

Detected by Coverity: CID 753101

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>