Implement PCI SR-IOV initialization methods

[rstone]

Summary

Implement the two new PCI methods used to initialize and uninitialize
SR-IOV on a PF. On initialization, the PF must allocate a VEB,
which is a virtual switch instance implemented by the hardware. The
PF's interface is made a child of this switch.

[rstone]

Undo ifx/vsi split

[jfv]

Don't see any issues, of course the proof will come in the actual use when we
have the infrastructure :)