[CIR[IR] Remove duplicit optional of struct ast parameter.

Author: xlauko

clang/include/clang/CIR/Dialect/IR/CIRTypes.td

@@ -112,7 +112,7 @@ def CIR_StructType : CIR_Type<"Struct", "struct",
     "bool":$body,
     "bool":$packed,
     "mlir::cir::StructType::RecordKind":$kind,
-    OptionalParameter<"std::optional<ASTRecordDeclInterface>">:$ast
+    "std::optional<ASTRecordDeclInterface>":$ast
   );
 
   let hasCustomAssemblyFormat = 1;