[clang] [llvm] [RISCV][Scheduler] Add scheduler definitions for the Q extension (PR #139495)

[Iris Shi via cfe-commits]

el-ev wrote:

### Merge activity

* **May 14, 10:53 PM EDT**: [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/139495) couldn't merge this PR because it had conflicts with the trunk branch.


https://github.com/llvm/llvm-project/pull/139495