Add PCI device filters support

Cloud administrator may decide the devices that can be assigned to VM
based on vendor_id or device_id etc.

This is whitelist based filter. No device will be assigned
except explicitly defined.

The configuration option 'pci_passthrough_whitelist' can be defined multi
times, each for one type of device.

bp:pci-passthrough-base

Change-Id: I03f2a0c098198a32abedff0773e9f94e3d7d2f28
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Signed-off-by: Yongli He <yongli.he@intel.com>
Merge "Add PCI device filters support"