Stop q-domua process when XenServer is used

When using XenServer, it will create two neutron-openvswitch-agent
q-agt and q-domua even it's single box environment, but it didn't
stop the q-domua, this patch is to stop q-domua in unstack.sh

Change-Id: I511ed534bfb7d5fe6136f6a0b33f1d749d30862c
Closes-Bug: #1631721
diff --git a/lib/neutron-legacy b/lib/neutron-legacy
index 9e926a0..938d566 100644
--- a/lib/neutron-legacy
+++ b/lib/neutron-legacy
@@ -511,6 +511,10 @@
 
 function stop_mutnauq_l2_agent {
     stop_process q-agt
+
+    if [ "$VIRT_DRIVER" = 'xenserver' ]; then
+        stop_process q-domua
+    fi
 }
 
 # stop_mutnauq_other() - Stop running processes (non-screen)