fix bugs in mpc demo

python/paddle_fl/mpc/examples/mnist_demo/run_standalone.sh

@@ -61,8 +61,8 @@ fi
 $REDIS_BIN -h $SERVER -p $PORT flushall
 
 # remove temp data generated in last time
-LOSS_FILE="/tmp/uci_loss.*"
-PRED_FILE="/tmp/uci_prediction.*"
+LOSS_FILE="/tmp/mnist_output_loss.*"
+PRED_FILE="/tmp/mnist_output_prediction.*"
 if [ "$LOSS_FILE" ]; then
         rm -rf $LOSS_FILE
 fi