libxl__device_nic_devname used to hardcode backend network interfaces
as "vif<domid>.<handle>", remove this limitation and allow libxl to
deal with OS-specific interface names.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>