Add null to driverlistcommand completer

Change-Id: I4186c9cc6fa19fb83437e5d5704d5ce48c50b84c
diff --git a/cli/src/main/resources/OSGI-INF/blueprint/shell-config.xml b/cli/src/main/resources/OSGI-INF/blueprint/shell-config.xml
index 92271f2..03eede3 100644
--- a/cli/src/main/resources/OSGI-INF/blueprint/shell-config.xml
+++ b/cli/src/main/resources/OSGI-INF/blueprint/shell-config.xml
@@ -114,6 +114,7 @@
             <action class="org.onosproject.cli.net.DriversListCommand"/>
             <completers>
                 <ref component-id="driverNameCompleter"/>
+                <null/>
             </completers>
         </command>