(VOL-4968) add uni and optional vlan args to the bbsim igmp keywords

Change-Id: I6f8d62855e6ef27acb6469b2628d5258216a566f
diff --git a/tests/scale/Voltha_Scale_Tests.robot b/tests/scale/Voltha_Scale_Tests.robot
index e2ef26e..b794b20 100755
--- a/tests/scale/Voltha_Scale_Tests.robot
+++ b/tests/scale/Voltha_Scale_Tests.robot
@@ -382,5 +382,5 @@
     [Documentation]    Performs Igmp Join for all the ONUs of an OLT (based on Rest Endpoint)
     [Arguments]    ${bbsim_rel_session}    ${onu_list}    ${task}
     FOR    ${onu}    IN    @{onu_list}
-        JoinOrLeave Igmp Rest Based    ${bbsim_rel_session}    ${onu}    ${task}    224.0.0.22
+        JoinOrLeave Igmp Rest Based    ${bbsim_rel_session}    ${onu}    0    ${task}    224.0.0.22
     END