Skip default lanes dup check (sonic-net#3489)

* Add namespace check for multiasic
* Skip Default lane duplication check.

Author: xincunli-sonic

generic_config_updater/gu_common.py

@@ -239,7 +239,8 @@ def validate_lanes(self, config_db):
             for port in port_to_lanes_map:
                 lanes = port_to_lanes_map[port]
                 for lane in lanes:
-                    if lane in existing:
+                    # default lane would be 0, it does not need validate duplication.
+                    if lane in existing and lane != '0':
                         return False, f"'{lane}' lane is used multiple times in PORT: {set([port, existing[lane]])}"
                     existing[lane] = port
         return True, None

tests/generic_config_updater/gu_common_test.py

@@ -361,6 +361,13 @@ def test_validate_lanes__same_valid_lanes_multi_ports_no_spaces__failure(self):
             }}
         self.validate_lanes(config, '67')
 
+    def test_validate_lanes_default_value_duplicate_check(self):
+        config = {"PORT": {
+            "Ethernet0": {"lanes": "0", "speed": "10000"},
+            "Ethernet1": {"lanes": "0", "speed": "10000"},
+            }}
+        self.validate_lanes(config)
+
     def validate_lanes(self, config_db, expected_error=None):
         # Arrange
         config_wrapper = gu_common.ConfigWrapper()