Revert "Remove unused includes from runner (#14338)"

This reverts commit b80ac3b.

Author: lucylq

extension/llm/runner/util.h

@@ -7,6 +7,8 @@
  */
 
 #pragma once
+#include <executorch/extension/llm/runner/constants.h>
+#include <executorch/extension/llm/runner/multimodal_prefiller.h>
 #include <executorch/extension/tensor/tensor.h>
 #include <executorch/runtime/platform/compiler.h>
 #include <stdio.h>