linkmonitor: fix reported device name of vlans and macvlans

Previously, vlans and macvlans would get the event name reported as:
- 'foo@bar', where bar is the device the foo macvlan sits on.
- 'bond777.555@bond777', where bond777 is the device the 555 vlan
  sits on.

After this fix, both devices would be properly reported as:
- foo
- bond777.555

Since we use the ifindex, we'll add it to the event.

Change-Id: Ieaeab6adc30a80b70e9e967768c10b3fea65aa16
Signed-off-by: Antoni S. Puimedon <asegurap@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/22061
Reviewed-by: Dan Kenigsberg <danken@redhat.com>