services: Open vSwitch: Provide a default configuration.

* gnu/services/networking.scm (openvswitch-service-type): Provide
OPENVSWITCH-CONFIGURATION as a default value.
* gnu/tests/networking.scm (%openvswitch-os): Don't configure the service.

gnu/services/networking.scm

@@ -1154,7 +1154,8 @@ (define openvswitch-service-type
    (description
     "Run @uref{http://www.openvswitch.org, Open vSwitch}, a multilayer virtual
 switch designed to enable massive network automation through programmatic
-extension.")))
+extension.")
+   (default-value (openvswitch-configuration))))
 
 ;;;
 ;;; iptables

gnu/tests/networking.scm

@@ -178,9 +178,7 @@ (define %openvswitch-os
    (static-networking-service "ovs0" "10.1.1.1"
                               #:netmask "255.255.255.252"
                               #:requirement '(openvswitch-configuration))
-   (service openvswitch-service-type
-            (openvswitch-configuration
-             (package openvswitch)))
+   (service openvswitch-service-type)
    openvswitch-configuration-service))
 
 (define (run-openvswitch-test)