Fix test_buffer_deployment case NoneType issue (#6050)

What is the motivation for this PR?
Case test_buffer_deployment failed on the Broadcom devices.

How did you do it?
Init lossless headroom data for non-mellanox device

How did you verify/test it?
Re-run the failure case

tests/qos/test_buffer.py

@@ -295,6 +295,7 @@ def setup_module(duthosts, rand_one_dut_hostname, request):
     duthost = duthosts[rand_one_dut_hostname]
     detect_buffer_model(duthost)
     if not is_mellanox_device(duthost):
+        load_lossless_headroom_data(duthost)
         yield
         return
 
@@ -2427,7 +2428,7 @@ def _check_port_buffer_info_and_return(duthost, table, ids, port, expected_profi
         else:
             if is_mellanox_device(duthost):
                 buffer_items_to_check = buffer_items_to_check_dict["down"]
-            elif is_broadcom_device(duthost) and (asic_type in ['td2'] or speed <= '10000'):
+            elif is_broadcom_device(duthost) and (asic_type in ['td2', 'td3'] or speed <= '10000'):
                 buffer_items_to_check = [(None, None, None)]
             else:
                 buffer_items_to_check = [('BUFFER_PG_TABLE', '3-4', profile_wrapper.format(expected_profile))]