add SN5640 to the margin setting list

Author: JibinBao

tests/saitests/py3/sai_qos_tests.py

@@ -5192,7 +5192,7 @@ def runTest(self):
                 assert (q_wm_res[queue] <= (margin + 1) * cell_size)
             elif pkts_num_fill_min:
                 assert (q_wm_res[queue] == 0)
-            elif 'cisco-8000' in asic_type or "SN5600" in hwsku or "SN5400" in hwsku or "SN5610" in hwsku:
+            elif 'cisco-8000' in asic_type or "SN56" in hwsku or "SN5400" in hwsku:
                 assert (q_wm_res[queue] <= (margin + 1) * cell_size)
             else:
                 if platform_asic and platform_asic == "broadcom-dnx":