Changing the parsing of the PCI addresses to find and manage virtual functions for SR-IOV support

On a vNIC, the driver attaches and manages the virtual functions (VFs) through physical functions (PFs). The sysfs builds links under /sys/class/net/ of all PCI addresses attached to those functions. The way nova manages and threats those functions makes assumptions that different vendor NIC drivers follow the same pattern to build the path on the system.
The way it is implemented yet follows the way the Intel driver builds the path on the system.
The purpose of this blueprint is to allow nova to find and manage the VFs using the PCI addresses independently of the vendor NIC.