[llvm] [RISCV][RegAlloc] Add getCSRFirstUseCost for RISC-V (PR #131349)

[Michael Maitland via llvm-commits]

michaelmaitland wrote:

Adding a comment here for future reference: we should re-evaluate setting this option once the improvements to ShrinkWrapping land.

https://github.com/llvm/llvm-project/pull/131349