Use new pci device handling code in pci_manager

As we remove some pci device method from PCI device object,
update the pci manager accordingly.

Closes-Bug: #1273852

Change-Id: I0ec0e7b03625888a207918816b6e2d537b6d7d54
Remove the device handling from pci device object

Remove the device handling code at pci device object to make
it similar to other NovaObject.

Remove some usage in test cases.

Closes-Bug: #1273852

Change-Id: I4487ae0b36de18365d12593f480c05f0fe726769
Merge "Use new pci device handling code in pci_manager"
Merge "Remove the device handling from pci device object"