[Mellanox] Enable get_tx_fault support in CMIS cable host mgmt mode (s…

…onic-net#18984)

- Why I did it
Enable get_tx_fault support in CMIS cable host mgmt mode on Mellanox platforms

- How I did it
Use community get_tx_fault implementation instead of the dummy one

- How to verify it
API call and run API Test

Signed-off-by: Yuanzhe, Liu <yualiu@nvidia.com>

platform/mellanox/mlnx-platform-api/sonic_platform/sfp.py

@@ -1055,6 +1055,11 @@ def get_tx_fault(self):
             list: [False] * channels
         """
         api = self.get_xcvr_api()
+        try:
+            if self.is_sw_control():
+                return api.get_tx_fault() if api else None
+        except Exception as e:
+            print(e)
         return [False] * api.NUM_CHANNELS if api else None
 
     def get_temperature(self):
@@ -1155,7 +1160,6 @@ def get_xcvr_api(self):
             self.refresh_xcvr_api()
             if self._xcvr_api is not None:
                 self._xcvr_api.get_rx_los = self.get_rx_los
-                self._xcvr_api.get_tx_fault = self.get_tx_fault
         return self._xcvr_api
 
     def is_sw_control(self):