[llvm] [AMDGPU][test] fix the error case in update_mc_test_check script (PR #112731)

[Brox Chen via llvm-commits]

broxigarchen wrote:

> Needs a test using the `--llvm-mc-binary` option?

I am not sure if we can do this in the test here? since it requires a mc-binary location

https://github.com/llvm/llvm-project/pull/112731