Error seen in agent/bal when testing multiple multicast group for TT workflow

=== Setup ===

Three ONUs on ASFvOLT16.

ONU1 and ONU2 on PON0 and ONU3 on PON1.

=== Below is the test scenario ===

Two IP TV Groups - Group1 225.22.0.2 and Group2 224.8.7.6 

ONU1 subscribed to Group1, ONU2 to Group2 and ONU3 to Group2

At ONOS IGMP flow1 created pointing to the group1 and IGMP flow2 is created pointing to group2. Group1 created in ONOS with one buckets. Group2 is created with two buckets

At BAL Two pon ports have registered to the group2 and one pon port is registed to group1 on the BAL

ONU2 leaves the group2

At ONOS, one bucket should be cleared for group2 corresponding to ONU2 UNI port

On BAL the group should still exist and but only one PON port should still be registed to the group now

ONU3 leaves the group2

At ONOS, group2 should get deleted and also the IGMP flow2 pointing to the group should get deleted

On BAL the flow2 and group2 should get deleted.

ONU1 leaves the group1

At ONOS the IGMP flow1 should be deleted, followed by group1 delete

On BAL the IGMP flow1 is deleted and group1 will be deleted.

===== When ONU2 joins group2 below error is seen in BAL ===

[2638352: E SW_UTIL ] bal_dpp_flow.c 1167| Error, fail to add mc flow to vsi service tag list - please check the classifier
[2638352: E FLOW ] flow_fsm.c 412| error detected by switch util while adding flow
[2638352: E FLOW ] flow_fsm.c 311| *** Error detected during state processing

=== Agent flow is this ===

[2513350: E OPENOLT ] core_api_handler.cc 1988| -------> Flow add failed (flow_id 26) err: -11 <-------
[2513350: E OPENOLT ] core_api_handler.cc 1988| intf_id 0, onu_id 1, uni_id 0, port_no 0, cookie 31243723538750666
[2513350: E OPENOLT ] core_api_handler.cc 1988| flow_type multicast, queue_id 0, sched_id 0
[2513350: E OPENOLT ] core_api_handler.cc 1988| Ingress(intfd_type NNI, intf_id 0), Egress(intf_type unknown, intf_id 0)
[2513350: E OPENOLT ] core_api_handler.cc 1988| classifier(o_vid 550, o_pbits 0, i_vid 55, i_pbits 0, ether type 0x0)
[2513350: E OPENOLT ] core_api_handler.cc 1988| classifier(ip_proto 0x0, gemport_id 0, src_port 0, dst_port 0, pkt_tag_type DOUBLE_TAG)
[2513350: E OPENOLT ] core_api_handler.cc 1988| action(cmds_bitmask , o_vid 0, o_pbits 0, i_vid 0, i_pbits 0)