[mlir] fix python bindings cmake

Author: ftynse

mlir/python/CMakeLists.txt

@@ -108,7 +108,9 @@ declare_mlir_dialect_python_bindings(
   ADD_TO_PARENT MLIRPythonSources.Dialects
   ROOT_DIR "${CMAKE_CURRENT_SOURCE_DIR}/mlir"
   TD_FILE dialects/MemRefOps.td
-  SOURCES dialects/memref.py
+  SOURCES
+    dialects/memref.py
+    dialects/_memref_ops_ext.py
   DIALECT_NAME memref)
 
 declare_mlir_dialect_python_bindings(