Fix multinode scenario

devstack-gate should only be executed on the primary node, will cause
erros when run on the secondary.

Change-Id: Iebea66e25c81e1571a5506e3a6b4bf3b8195ddbd
diff --git a/playbooks/neutron-tempest-plugin-dvr-multinode-scenario/run.yaml b/playbooks/neutron-tempest-plugin-dvr-multinode-scenario/run.yaml
index c2d33a9..2102bb5 100644
--- a/playbooks/neutron-tempest-plugin-dvr-multinode-scenario/run.yaml
+++ b/playbooks/neutron-tempest-plugin-dvr-multinode-scenario/run.yaml
@@ -1,4 +1,4 @@
-- hosts: all
+- hosts: primary
   name: neutron-tempest-plugin-dvr-multinode-scenario
   tasks: