Nailgun should accept and store SR-IOV related info and configuration

Information from the nailgun-agent and user input should be stored in
`interface_properties` field of `NodeNICInterface`:

* Whether SR-IOV is enabled by user or not and number of enabled VFs
  (`sriov_numvfs`)

* Number of available virtual functions (`sriov_totalvfs`)

* SR-IOV availability (IOMMU groups should be checked)

* PCI-ID of NIC virtual functions of this NIC (it's same for all VFs)