Error "No such file or directory - /sys/class/net/*/device/sriov_numvfs" when deploying SR-IOV nodes

Issue

• Trying to deploy SR-IOV nodes with Mellanox ConnectX-3 (mlx4_core) failed with the following ERROR:

  ...
            "Error: Could not set 'present' on ensure: No such file or directory - /sys/class/net/ens6d1/device/sriov_numvfs at /etc/puppet/modules/tripleo/manifests
  /host/sriov.pp:22",
            "Wrapped exception:",
            "No such file or directory - /sys/class/net/ens6d1/device/sriov_numvfs",
            "Error: /Stage[main]/Tripleo::Host::Sriov/Sriov_vf_config[ens6d1:8]/ensure: change from absent to present failed: Could not set 'present' on ensure: No such file or directory - /sys/class/net/ens6d1/device/sriov_numvfs at /etc/puppet/modules/tripleo/manifests/host/sriov.pp:22",
  ...
  

• The sriov_numvfs file shows the VFs are not correctly configured:

  [root@computesriov-0 ~]# cat /sys/class/net/ens2/device/sriov_numvfs
  0
  [root@computesriov-0 ~]# cat /sys/class/net/ens6/device/sriov_numvfs
  0