fix a missed get_aten_mode_options spot (#8775)

This was the only spot that didn't use a tuple, so my find/replace missed it.

Author: swolchok

kernels/portable/cpu/util/targets.bzl

@@ -1,4 +1,4 @@
-load("@fbsource//xplat/executorch/build:runtime_wrapper.bzl", "runtime")
+load("@fbsource//xplat/executorch/build:runtime_wrapper.bzl", "get_aten_mode_options", "runtime")
 
 def define_common_targets():
     """Defines targets that should be shared between fbcode and xplat.
@@ -281,7 +281,7 @@ def define_common_targets():
     )
 
     # Utility functions that can be used by operators that perform reduction
-    for aten_mode in [True, False]:
+    for aten_mode in get_aten_mode_options():
         suffix = "_aten" if aten_mode else ""
         runtime.cxx_library(
             name = "reduce_util{}".format(suffix),