fix bug when generating event stream events serializer

Author: AllanZhengYP

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/HttpBindingProtocolGenerator.java

@@ -851,7 +851,7 @@ private void writeEventBody(GenerationContext context, StructureShape event) {
             SymbolProvider symbolProvider = context.getSymbolProvider();
             Symbol symbol = symbolProvider.toSymbol(event);
             // Use normal structure deserializer instead of event deserializer to deserialize document body.
-            String serFunctionName = ProtocolGenerator.getDeserFunctionName(symbol, context.getProtocolName());
+            String serFunctionName = ProtocolGenerator.getSerFunctionName(symbol, context.getProtocolName());
             writer.write("message.body = $L(input, context);", serFunctionName);
         }
     }