Update tutorial-arm-ethos-u.md (pytorch#12973)

Fix run.sh example usage

### Summary
[PLEASE REMOVE] See [CONTRIBUTING.md's Pull
Requests](https://github.com/pytorch/executorch/blob/main/CONTRIBUTING.md#pull-requests)
for ExecuTorch PR guidelines.

[PLEASE REMOVE] If this PR closes an issue, please add a `Fixes
#<issue-id>` line.

[PLEASE REMOVE] If this PR introduces a fix or feature that should be
the upcoming release notes, please add a "Release notes: <area>" label.
For a list of available release notes labels, check out
[CONTRIBUTING.md's Pull
Requests](https://github.com/pytorch/executorch/blob/main/CONTRIBUTING.md#pull-requests).

### Test plan
[PLEASE REMOVE] How did you test this PR? Please write down any manual
commands you used and note down tests that you have written if
applicable.

Author: psiddh

docs/source/tutorial-arm-ethos-u.md

@@ -334,9 +334,9 @@ Once the elf is prepared, regardless of the `.pte` file variant is used to gener
 ./run.sh --model_name=mv2 --delegate --target=ethos-u85-128
 ```
 
-- To run all the test models iteratively in a loop 
+- To run all the test models iteratively in a loop , simply run
 ```bash
-./run.sh --pte=mv2_arm_ethos_u55.pte --target=ethos-u55-128
+./run.sh
 ```
 
 Note that you could use `build_executor_runner.sh` and `run_fvp.sh` scripts in tandem by passing the relevant  --target argument (e.g., --target=ethos-u55-128), the correct FVP binary will be chosen automatically. For more details, see the [section on Runtime Integration](https://docs.pytorch.org/executorch/main/backends-arm-ethos-u.html#runtime-integration).