[llvm] Revert "Add HexagonGlobalScheduler pass (#180803)" (PR #181418)

[Brian Cain via llvm-commits]

androm3da wrote:

> [d0252a1](https://github.com/llvm/llvm-project/commit/d0252a1013e26a80204e723b0b0aaecfdc3b601a) could fix some (or all if we're lucky) of the problem(s) introduced

I'd say it makes sense to go ahead w/the revert but consider including some or all of the test/fixes above when re-applying.

https://github.com/llvm/llvm-project/pull/181418