Clean up code of virt_phy_sw_v2 module

 Removes two methods not used:
 * _get_all_segmentation_ids
 * _validate_vlan_id

 About log formatting:
 * In the __init__, '\n' can be removed from this line:
     LOG.debug(_("Loaded device plugin %s\n"),

Closes-Bug: 1180783

Change-Id: Ic0aea7e8016f198e2ba245c710e12bc490720039
Merge "Clean up code of virt_phy_sw_v2 module"