[mlir][nfc] Fix typo in LIT RUN line
Failing bot:
* https://lab.llvm.org/buildbot/#/builders/17/builds/6269
The offending test was added in:
* https://github.com/llvm/llvm-project/pull/129696
To fix this, use:
* `%mcr_aarch64_cmd` (which is what we used for ArmSVE e2e tests),
Instead of:
* `mlir-cpu-runner` (which was renamed to `mlir-runner` in #123776).
Committed without review due to being a trivial test update; if this
needs discussion, please ping me or leave a comment on GitHub.
