nodedev: add RDMA and tx-udp_tnl-segmentation NIC capabilities

nodedev: add RDMA and tx-udp_tnl-segmentation NIC capabilities

Adding functionality to libvirt that will allow
it query the interface for the availability of RDMA and
tx-udp_tnl-segmentation Offloading NIC capabilities

Here is an example of the feature XML definition:

<device>
<name>net_eth4_90_e2_ba_5e_a5_45</name>
  <path>/sys/devices/pci0000:00/0000:00:03.0/0000:08:00.1/net/eth4</path>
  <parent>pci_0000_08_00_1</parent>
  <capability type='net'>
    <interface>eth4</interface>
    <address>90:e2:ba:5e:a5:45</address>
    <link speed='10000' state='up'/>
    <feature name='rx'/>
    <feature name='tx'/>
    <feature name='sg'/>
    <feature name='tso'/>
    <feature name='gso'/>
    <feature name='gro'/>
    <feature name='rxvlan'/>
    <feature name='txvlan'/>
    <feature name='rxhash'/>
    <feature name='rdma'/>
    <feature name='txudptnl'/>
    <capability type='80203'/>
  </capability>
</device>