Fix to setup-vif-rules

change  bridge_name = "xenbr%s" % devid
to  bridge_name = get_bridge_name_vswitch(vif_name)

Devid is device number for domU (f.e. vif1.15; 15 - devid) and is definitely NOT a
xenbr number (xenbr0, xenbr1, etc).

This will fix broken Multi-Tenancy feature for xenbrX and vif1.X for X !=0.