Arm backend: Revert 5D-updates to EthosUBackend

[oscarandersson8218]

Revert 5D-updates to EthosUBackend.cpp. 5D inputs/outputs are currently not supported.

cc @digantdesai @freddan80 @per @zingo

[pytorch-bot]

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❌ 1 New Failure, 1 Cancelled Job

As of commit 8babd6e with merge base ed486c2 ():

NEW FAILURE - The following job has failed:

• trunk / test-arm-cortex-m-size-test / linux-job (gh)
  RuntimeError: Command docker exec -t 29635f33795ac4c563d57bf333e55a0b5aa6668426e0a5718ecb3569e6bf3eee /exec failed with exit code 1

CANCELLED JOB - The following job was cancelled. Please retry:

• trunk / test-models-macos (mobilebert, xnnpack-quantization-delegation) / macos-job (gh)
  ##[error]The operation was canceled.

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[oscarandersson8218]

Unrelated failures.