[lld] [lld][Mips] Remove signed range check for R_MICROMIPS_26_S1 (PR #228880)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> The commit message formatting is also poor (forced wrapping at 72 columns), an issue often caused by agentic coding tools.

Sorry if it's not clear. `retaining` and `calls` are on their own lines due to "Squash and merge"'s forced wrapping at 72 columns when your original patch description is not wrapped at 72.

https://github.com/llvm/llvm-project/pull/228880