Arm backend: Remove N=1 constraint for MaxPool2d on U55

[Erik-Lundell]

This is not needed anymore after Vela bump.

cc @digantdesai @freddan80 @per @zingo @oscarandersson8218

[pytorch-bot]

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❌ 3 Cancelled Jobs, 1 Pending, 1 Unrelated Failure

As of commit 8f948d2 with merge base 30d4cc8 ():

CANCELLED JOBS - The following jobs were cancelled. Please retry:

• trunk / test-models-macos (cmake, qwen2_5, portable, macos-m1-stable, 90) / macos-job (gh)
  ##[error]The operation was canceled.
• trunk / test-models-macos (cmake, resnet18, xnnpack-quantization-delegation, macos-m1-stable, 90) / macos-job (gh)
  ##[error]The operation was canceled.
• trunk / test-models-macos (cmake, softmax, portable, macos-m1-stable, 90) / macos-job (gh)
  ##[error]The operation was canceled.

BROKEN TRUNK - The following job failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• trunk / test-pip-install-editable-mode-macos / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1

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[zingo]

Failed MacOS tests are unrelated

[swolchok]

JFYI this function could be written more idiomatically as return all([1 <= dim <= 65536 for dim in shape[1:]])