Core ML Has Added Index_Put Support, No Need to Skip Anymore (#2975)

Summary:
It was a workaround to skip `aten.index_put` op in Core ML delegation, at the cost of partitioning the Llama model into 13 pieces.

For better performance, we prefer to delegate the whole model to Core ML. Since Core ML has added the [necessary support](apple/coremltools#2190), it is time to revert this workaround

Pull Request resolved: #2975

Reviewed By: kirklandsign

Differential Revision: D56002979

Pulled By: cccclai

fbshipit-source-id: e7a7c8c43706cb57eba3e6f720b3d713bec5065b

examples/models/llama2/export_llama_lib.py

@@ -605,9 +605,6 @@ def _export_llama(modelname, args) -> str:  # noqa: C901
         partitioners.append(
             # pyre-ignore: Undefined attribute [16]: Module `executorch.backends` has no attribute `apple`
             CoreMLPartitioner(
-                skip_ops_for_coreml_delegation=[
-                    "aten.index_put.default",
-                ],
                 compile_specs=compile_specs,
             )
         )