pci: eliminate memory leak in virPCIDeviceReattach

pci: eliminate memory leak in virPCIDeviceReattach

virPCIDeviceReattach was making the assumption that the dev object
given to it was one and the same with the dev object on the
inactiveDevs list. If that had been the case, it would not need to
free the dev object it removed from the inactive list, because the
caller of virPCIDeviceReattach always frees the dev object that it
passes in. Since the dev object passed in is *never* the same object
that's on the list (it is a different object with the same name and
attributes, created just for the purpose of searching for the actual
object), simply doing a "ListSteal" to remove the object from the list
results in one leaked object; we need to actually free the object
after removing it from the list.