[Vlan] Add barefoot platform to vlan QinQ test case (#3745)

Approach
What is the motivation for this PR?
Run test_vlan_tc6_tagged_qinq_switch_on_outer_tag

How did you do it?
How did you verify/test it?
Run test case on t0 topo:
vlan/test_vlan.py::test_vlan_tc6_tagged_qinq_switch_on_outer_tag PASSED

Signed-off-by: Andrii-Yosafat Lozovyi <[email protected]>

tests/vlan/test_vlan.py

@@ -412,7 +412,7 @@ def test_vlan_tc4_tagged_non_broadcast(ptfadapter, vlan_ports_list):
         if "Did not receive expected packet on any of ports" in str(detail):
             logger.error("Expected packet was not received")
         raise
-    
+
     logger.info("One Way Tagged Packet Transmission Works")
     logger.info("Tagged packet successfully sent from port {} to port {}".format(src_port[0], dst_port))
 
@@ -451,7 +451,7 @@ def test_vlan_tc5_untagged_non_broadcast(ptfadapter, vlan_ports_list, duthost):
     src_port = ports_for_test[0]
     dst_port = ports_for_test[-1]
 
-    src_mac = ptfadapter.dataplane.get_mac(0, src_port[0]) 
+    src_mac = ptfadapter.dataplane.get_mac(0, src_port[0])
     dst_mac = ptfadapter.dataplane.get_mac(0, dst_port[0])
 
     transmit_untagged_pkt = build_icmp_packet(vlan_id=0, src_mac=src_mac, dst_mac=dst_mac)
@@ -494,7 +494,7 @@ def test_vlan_tc6_tagged_qinq_switch_on_outer_tag(ptfadapter, vlan_ports_list, d
     """
 
     # Add more supported platforms to the list as they are tested
-    qinq_switching_supported_platforms = ['mellanox']
+    qinq_switching_supported_platforms = ['mellanox', 'barefoot']
     if duthost.facts["asic_type"] not in qinq_switching_supported_platforms:
         pytest.skip("Unsupported platform")