Update test_ccmis.py

Fixing the test code failure case.

Author: jaganbal-a

tests/sonic_xcvr/test_ccmis.py

@@ -631,19 +631,23 @@ def test_get_transceiver_pm(self, mock_response, expected):
         (1, 1),
     ])
     def test_freeze_vdm_stats(self, mock_response, expected):
+        original_api = self.api.util_status_check_with_retry
         self.api.util_status_check_with_retry = MagicMock()
         self.api.util_status_check_with_retry.return_value = mock_response
         result = self.api.freeze_vdm_stats()
+        self.api.util_status_check_with_retry = original_api
         assert result == expected
 
     @pytest.mark.parametrize("mock_response, expected", [
         (0, 0),
         (1, 1),
     ])
     def test_unfreeze_vdm_stats(self, mock_response, expected):
+        original_api = self.api.util_status_check_with_retry
         self.api.util_status_check_with_retry = MagicMock()
         self.api.util_status_check_with_retry.return_value = mock_response
         result = self.api.unfreeze_vdm_stats()
+        self.api.util_status_check_with_retry = original_api
         assert result == expected
 
     @pytest.mark.parametrize("input_param, mock_response, expected",[