[llvm] [AVR] Force relocations for non-encodable jumps (PR #121498)

[Fangrui Song via llvm-commits]

MaskRay wrote:

I am late to see this. The additional argument introduces unnecessary complexity across all backend implementations. To simplify, I propose removing it and instead creating a new `MCValue` with the Cst field adjusted to the desired value. This eliminates the need for the extra argument in backend hooks.

I am making the simplification.

https://github.com/llvm/llvm-project/pull/121498