[llvm] [NFC][AMDGPU] print more info when debugging InsertWaitCnts pass (PR #144629)

[Sameer Sahasrabuddhe via llvm-commits]

ssahasra wrote:

- Removed some of the extra new lines. The log is still quite readable.
- Also eliminated the .def file in favour of a local macro.

https://github.com/llvm/llvm-project/pull/144629