fix undef var (#34048)

* fix undef var

* fix undef var

python/paddle/fluid/contrib/slim/quantization/cal_kl_threshold.py

@@ -12,8 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
 import math
 import numpy as np
+from ....log_helper import get_logger
+
+_logger = get_logger(
+    __name__, logging.INFO, fmt='%(asctime)s-%(levelname)s: %(message)s')
 
 __all__ = ['cal_kl_threshold']