Fix unless check when creating ovs peer interface

Interface name was hardcoded when checking if peer is set for
ovs interface.
This patch unhardcode interface name.

Change-Id: Id465d5f84751b5516aebc9d80716d21d14e56abc

linux/network/interface.sls

 ovs_port_set_peer_{{ interface_name }}:
   cmd.run:
   - name: ovs-vsctl set interface {{ interface_name }} options:peer={{ interface.peer }}
-  - unless: ovs-vsctl show | grep -A 2 'Interface floating-to-prv' | grep {{ interface.peer }}
+  - unless: ovs-vsctl show | grep -A 2 'Interface {{ interface_name }}' | grep {{ interface.peer }}
 
 {%- else %}