[llvm] [RISCV][TTI] Add checks for invalid cast operations (PR #88854)

[Shih-Po Hung via llvm-commits]

arcbbb wrote:

> TTI should assert sanity of the API, and we should fix the caller. It's very likely there's a higher level semantics bug in the LV causing this, and we need to find and fix that one.

OK, I create #89161 for this.

https://github.com/llvm/llvm-project/pull/88854