[StreamingMaxpool] Added empty functions for abstract methods in HLSCustomOp class

src/finn/custom_op/fpgadataflow/streamingmaxpool_batch.py

@@ -69,6 +69,12 @@ class StreamingMaxPool_Batch(HLSCustomOp):
 
         return info_messages
 
+    def bram_estimation(self):
+        pass
+
+    def lut_estimation(self):
+        pass
+
     def global_includes(self):
         self.code_gen_dict["$GLOBALS$"] = ['#include "maxpool.h"']