[ONOS-7279] Fix for illegal state exception when deactivating driver providers

Change-Id: I9a8c16e33cac40b91c2b6f405e66f94bcdf5e0e0
diff --git a/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java b/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java
index 47623a7..994303e 100644
--- a/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java
+++ b/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java
@@ -165,6 +165,7 @@
 
     @Deactivate
     public void deactivate() {
+        driverProvider.terminate();
         deviceService.removeListener(deviceListener);
         cfgService.unregisterProperties(getClass(), false);
         deviceInstallers.shutdownNow();